The fairies from Mirumo De Pon! They're all pretty much tied to their favorite snacks, especially Mirumo and Murumo, to the point were all you need to do to get them to do what you want is offer them a large enough amount of the treat in question. Mirumo and chocolate, Murumo and marshmallows, Rirumu and cream puffs, Yashichi and karintou. Although Yashichi is known more for his penchant for panties than his choice snack, come to think of it.
The favorite food of Doremi from Ojamajo Doremi is steak, and one of her image songs was even about her love of steaks. Unfortunately for her, it's a Running Gag that someone always eats her share of steak on the rare occasions it's served at the Harukazes' home, so she's only ever actually had a single bite of steak onscreen. There's also Aiko's more understated love for takoyaki, and in Motto, Hana-chan has a Sweet Tooth for pudding.
Also Momoko with her strawberry tart sweetness and sourness.
In InuYasha Shippo likes candy, particularly lollipops. Inuyasha himself seems to have a fondness for Ramen Instant Noodles in the anime, which the fandom exaggerates to addiction. Both were introduced to said foods by Kagome, who brings them from home on a regular basis.
Lapis of Detatoko Princess is addicted to pudding. This need drives the story much of the time.
Several characters in Death Note had a special interest in certain foods:
Ryuk adores apples and goes through withdrawals when forced to go without them. Since shinigami don't actually need to eat, apples are more like a drug to them than food. The postscript chapter suggests that all shinigami (or at least the Shinigami King) are the same: In the main story, he wouldn't give out any more Death Notes because of Ryuk... in the postscript chapter, he'd trade one for a couple apples.
Another Shinigami who tried to copy Ryuk by giving a Death Note to another mortal with notably less success chows down on bananas instead. Fruit in general might be addictive to the Shinigami.
Justified at one point when Ryuk shows Light what a Shinigami World apple is like - it's withered and tastes like sand. Food from Earth is a massive change to them.
In the ''How To Read'' guidebook, the author speculates that Ryuk might associate the red of apples with life-blood, which a Shinigami would naturally be driven to consume.
L has a pronounced sweet tooth and gorges himself on various sweets. He burns off the excess calories by thinking really hard. Actually justified, since about 50% of blood sugar is used by the brain...
Mello is a chocoholic. In the anime, the snapping sound he makes when biting into a bar of chocolate is practically his Leitmotif. In the manga, a huge delivery of chocolate is the clincher to pinning down his hideout.
Also of note is Yai/Yaito's love for Strawberry Milk.
Each of the mascot characters in Yes! Precure 5 has a different favorite snack. Coco likes choux a la creme, Nuts likes mamedaifuku (which can be sold at his girlfriend's family's store; this is made out to be a sign that they're destined), Milk likes chocolate, and Syrup likes (appropriately enough) pancakes.
In Galaxy Angel, Millefeuille loves pastries and sweets in general, Ranpha loves anything that's extremely spicy (And the others dread allowing her to cook), Mint adores junk foods such as potato chips and jelly beans, Forte has a soft spot for Oden stew, and Vanilla will eat just about everything (Including making a literal Chew Toy of Normad when starving), but prefers vegetarian dishes.
All variants and incarnations of Desty Nova (except the uber-evil Super Nova as of the moment) of Battle Angel Alita have an infamous love for flan. It goes to such lengths that Super Nova apparent lack of a flan-eating habit has become the indication of his evilness.
Digimon Savers's Agumon and fried eggs, Sarah/Sayuri's if at all possible.
The Bridge Bunnies are fond of manju (though it doesn't come up as much as Agumon and fried eggs.)
In Digimon Tamers, bread is pretty much Guilmon's favorite. He likes it so much that Takato's parents, who own a bakery, make him special bread shaped like his head and named after him. At least in the dub, he also likes peanut butter a lot.
And in Digimon Adventure 02, Veemon's favorite food is chocolate and Hawkmon is absolutely nuts about pickled gourd rolls. Armadillomon's favorite is the ohagi Iori's mom makes, but he's just happy to have any food at all.
There's a scene in the original where the kids discuss their recipes to cook eggs. Each Digidestined has their favorite, though Mimi grosses everyone out when she explains hers, which involved maple syrup, whipped cream and a cherry. Aside of that, Mimi loves tuna and mayo riceballs and goes googly-eyed in 02 when Miyako gives her some.
Actually, if I remember right, Mimi's egg recipe grossed everyone out but T.K. and he actually thought it sounded good but that might have been because he had a pretty big Sweet Tooth in the first season.
Digimon Frontier JP Shibayama was almost always seen with a chocolate bar in hand.
C.C. of Code Geass and pizza, but especially Pizza Hut. Hell, it's pretty much everybody's favorite food in the world of Code Geass. There is even an attempt of cooking the world's biggest pizza in Episode 21 and another in R2 Episode 5. Support the rebellion! Eat at Pizza Hut!
Kinniku Mantaro/Kid Muscle of Kinnikuman Ni-sei/Ultimate Muscle loved kalbi-don (Korean style grilled short-ribs and rice) so much, he had a song for it. And his dad Kinniku Suguru / King Muscle loved gyuudon (beef and rice) and also had a song for it. Like father, like son.
Pokémon is only loosely based off its source material (the games), thus even things in filler are canon (though some things are contradicted later in the series due the writers' forgetfulness).
Was subtly shown again, early in the Hoenn arc. In a small throwaway scene Pikachu can be seen holding a bottle of ketchup again, and this time it looked like he was sucking at the contents with a straw.
To be fair, ketchup does completely dominate the taste of anything it's put on, (which is why it's in a category with chili and ranch dressing as "things you put on bad food to make it edible"), so Pikachu eating it straight could just be him cutting out the hassle.
Thanks to Max, chocolate has become the Trademark Favorite Food of Lucario, when he gave the Fish Out of Temporal Water Lucario his first chocolate bar during the eighth movie. This was referenced in a later Diamond and Pearl episode, where Jessie tried bribing Maylene's Lucario to join them with a chocolate bar.
Also, more than one murder centers around the victim's favorite food or drink being laced with poison. So far some of the poisoned foods/drinks are: lemon tea, chocolate and cream cake, rice balls, soda, cherry pie...
The gag went as far as Tamaki buying her an ootoro-shaped ring during New Year's! Tamaki also has a well-known love of commoner's food and never turns down the chance to try some. The character pages at the end of volume one state each character's favorite foods.
The entire club is fascinated by Instant Coffee, which they think is an absolutely brilliant invention if one doesn't have time to grind actual beans (like commoners). They've more or less made it the "official drink of the Host Club".
In Eyeshield 21 Monta loves bananas, Mamori loves cream puffs, Marco loves cola, and Hiruma gets pissy if he doesn't have sugarless gum to chew.
Horo of Spice and Wolf gets excited over a lot of food, but none more so than apples, preferably straight. Her love of apples is even played up in the ending theme song.
Bob Poundmax in Gungrave loves fried chicken drumsticks. It's very rare for him to be seen without a chicken drumstick in his hand. Although he doesn't so much as chew the drumsticks as he just inhales them by the bucketful.
Half-alien teacher Mizuho Kazami of Please Teacher! eats pocky (or, actually, the similarly-named-but-not-trademark-infringing "Pochy") because it reminds her of her father, who was human. In the sequel Please Twins!, Miina Miyafuji has a similar attachment to Pretz (or, as it's called in the show, "Prech"), though her preference isn't similarly explained.
In School Rumble, much is made of the various male characters' preference for curry vs. beef-and-potato stew. Karasuma, the oblivious target of main character Tenma Tsukamoto's love, is the most food-obsessed, at one point stating he prefers curry to poor Tenma.
Eiichiro Oda, in his SBS Question Corner, once listed each main One Piece character's favorite food:
Monkey D. Luffy — Meat. To the point that when he prepares to take back everything that was stolen from them on Thriller Bark, he prioritizes them as "meat, Nami, and shadows". This did not go unlampshaded. The One Piece-Toriko crossover shows that Luffy's perfect meal consists entirely of meat—including the dessert and the beverage.
Roronoa Zoro — White rice, sea king meat, and anything that compliments ale
Nami — Mainly oranges as well as other kinds of fruit
Usopp — Pike from an autumn island as well as other fish of the season, hates mushrooms
Sanji — Spicy seafood pasta and food that compliments black tea
Nico Robin — Sandwiches, cakes that aren't too sweet and food that complements coffee
Franky — Hamburgers, french fries and food that complements cola
Brook — Tea and takoyaki
Big Bad and Evil Counterpart Blackbeard is as fond of cherry pie as Luffy is with meat. Actualy, this was used in the scene where they met each other: they were at the same restaurant, asked for the same order of meat and cherry pie, gushed over their own favorite foods and then insulted the other's, and got into a fistfight because of the last part.
In Kimi ni Todoke, Chizuru Yoshida's affection for her childhood friend Ryu Sanada led her to spend much of her youth at his family's ramen shop, to the point that she jokingly says she might want to "be a ramen" when she grows up.
Viewtiful Joe, in the anime, is nigh-obsessive about cheeseburgers.
Plue from Rave Master and sweets, with lollipops being the highest on his list.
Yuuko and the black Mokona from Xxx HO Li C are often asking for more liquor. Doesn't seem to impact their ability to run the shop, though.
In Sailor Moon All of the senshi have a favorite food (listed in their character profiles, but they don't show up in the manga or anime):
Moon/Usagi loves sweets (like cake and ice cream) so much, she even lists it as a hobby.
Chibi-Moon/Chibiusa loves Pudding and Pancakes. The manga profiles also list the food they hate the most. Ironically, Chibi-Usa and Usagi both list this as Carrots. (Usagi means Rabbit...)
Mercury/Ami loves Sandwiches (because she can eat one with a hand while holding a book in the other) and anmitsu (A Japanese Dessert).
Mars/Rei loves Fugu (a blowfish which is highly toxic and considered a delicacy in Japan).
Jupiter/Makoto loves All foods, cherry pie and meatloaf in particular.
Venus/Minako likes curry rice and ramen.
Neptune/Michiru: Sashimi (A type of Raw fish often confused for sushi in the west)
Pluto/Setsuna: Green Tea
Saturn/Hotaru: Soba (buckwheat) noodles
Mamoru/Tuxedo Mask: Never really got one, but the anime frequently showed him drinking coffee. It was even used in a joke where in a romantic moment alone with Usagi he suddenly abandoned her to go to the kitchen and drink more coffee.
Jack Atlas has two; Blue-Eyes Mountain Coffee and cup ramen.
Cup ramen appears to be a favorite for multiple characters, Jack, Yusei, Bruno, Crow and Jeager (Lazar) are all shown to adore the stuff.
In Yu Gi Oh Zexal, Yuma eats rice balls as snacks, often in the middle of a duel for energy ("duel fuel", as he calls them). Astral likes them too, although he can only experience the sensation of eating when he and Yuma share the same body in Zexal mode.
Only in Gintama can a character consume revolting quantities of mayonaise and still be badass. Hijikata's lighter is even shaped like a mayo bottle.
Also, Okita's sister Mitsuba loves super spicy crackers. Considering Gintama is a Gag Series, this particular gag was used very effectively for humor and drama.
Kagura and her sukonbu (pickled seaweed).
Yamazaki and AN-PAN AN-PAN ANPANANPANANPANANPANANPANANPANANPANANPANANPANANAPAN...although that may just a recent thing.
Yamazaki actually hates anpan. He only eats it when he is on mission, because he thinks that it is what a spy should eat.
Sa-chan and natto (fermented soybeams. They look icky), to the point of being named the "natto ninja" in one chapter.
Don't forget the protagonist himself; Gintoki and Chocolate Parfaits, and pretty much any sweets. To the point that his parallel to Hijikata's Special consist of red bean paste on rice.
Tomie demands foie gras and caviar a few times, although it is uncertain whether she likes it or just wants to have the most expensive things, seeing as she at one point in the series says that she's grown tired of eating it.
Erza from Fairy Tail loves strawberry cake; when someone makes her drop it, RUN.
Natsu loves anything that's covered in fire. Justified as it's his Power-Up Food.
The eponymous character from Oruchuban Ebichu loves camembert cheese, syrup and ice cream.
Ferris Eris of The Legend of the Legendary Heroes really loves dango (a type of Japanese dumpling). She asks for them as payment from Sion to help track down the person trying to kill him, and later (earlier from the audience's perspective perspective, since that happened in a flashback) refers to him as a "devil" for not paying up.
Subverted in Darker Than Black with Burger-kun. He has a renumeration of eating a hamburger after each use of his super speed. He may have liked them before, but now he is just sick of them.
"You're Cherry but you like bananas? You're weird."
Yukari-Sensei from Azumanga Daioh REALLY likes Snow crab and Matsusaka beef, so much so that she will beat the shit out of you if you've had it before her.
In another scene, the characters actually began to discuss their favorite foods. Chiyo's favorite is meatballs (which got her teased for being a little kid by Tomo), and Tomo's favorite are bananas (which likewise got her labeled an idiot).
Trigun's Vash has a fondness for doughnuts. Early parts of the series frequently used the running gag of him "accepting" them as a gift when they really were meant for someone else. Even in the latter part of the series, he still manages to joyously gorge himself on them.
The doughnuts were intended as a peace offering for Vash. Milly just didn't know he was the Vash the Stampede they'd been looking for.
Yumekui Merry is also addicted to doughnuts. The first time she bites into one, she declares it the best thing she's ever eaten in her life and calls them "Reality's treasure"... which gives one to wonder what sort of things, exactly, they usually eat in Dream Land.
Hazuki from Ame Nochi Hare enjoys chocolate so much that he will always keep some with him all the time.
Bamboo shoots is the favorite food of Sei from Koihime†Musou. It's almost taken to insane levels about her obssession with bamboo shoots. For example, don't insult bamboo shoots, or eat spoiled ones without asking, or YOU WILL PAY!
Shinsuke Maki is quite fond of sandwiches, as he would make anything into one.
Karl Lichter von Randoll absolutely loves black tea, to the point he would drink tea in pit lanes, during pit stops and even in the middle of the races.
Most of the characters have their favorite foods described in their profiles: Hayato and curry rice, Asuka and cake, Shinjyo and rice balls (particularly Miki's rice balls), Osamu and Asuka's cooking (which is rather odd as Asuka's a Lethal Chef), Miki and rice, tea and rice crackers, Kyoko and Italian cuisine, Henri and all kinds of sweets and pastries, Clair and pie, Gudelhian and ice cream and almost all Japanese foods, Heinel and kaiseki (traditional Japanese multi-course meals), Bootsvorz and anything spicy and super-sweet, Phill and his caregiver's cooking, Leon and his mother's stew, Marie and fish and vegetables.
Special A lists all the characters' favorites, but the one that's most notable is Kei Takishima, who prefers the cooking of his crush Hikari Hanazono over everything else in existence. He's quite literally blind to the fact that she's actually a Lethal Chef; everyone thinks he's insane when he says that she's the best cook in the world.
There are quite a few in Metal Fight Beyblade: Ginga and hamburgers, Yuu and ice cream, Doji and orange juice, Tobio and his ever-present blue lollipop, Masamune and those spicy sticks he's always munching on...
Angel Beats! has Kanade's Mapo Tofu, seemingly the only thing she ever eats. As a bonus, it's a metaphor for her personality. It's painfully spicy at first, but has an unexpectedly delicious aftertaste; just like how Kanade fights the Battlefront for a while, but eventually joins them and turns out to have been trying to help them the whole time.
The most noticeable and plot-relevant case is tacos for Yuuki, and she plays at her best after eating one. Alternatively, anything with octopus (tako) will do in a pinch.
Choe Myeng-hwa of the Rinkai team has come to like salmon and herring roe since coming to Japan. This is slightly downplayed, because her teammates are slightly surprised to hear about that detail when the announcers talk about her.
Haru of Eisui is often seen eating some muscovado chips. She shares some with Hisa during the break after their match, and when Hisa says they taste good, the normally expressionless Haru smiles.
Kouko Fukuyo, a mahjong commentator, has a fridge full of apple juice or mixes with apple juice.
Kill la Kill: Ryuko and Mako eat their mother's croquettes (Made of mystery things that are deep-fried in mashed potatoes, yet SOMEHOW it's never poisoned cooking) every day. Satsuki likes bitter tea. Turns out they go together very well.