These are what we call the 'YMMV items.' Things that some people find in this work. We call them 'your mileage might vary' because not everyone sees these things in the same way. This starts discussions in the trope lists, a thing we don't want. Please use the discussion page if you'd like to discuss any of these items.
Zangief is always a fan favorite, even though he's never been in a leading role. Fans clamor for him whenever he's missing from a game, to the point that neither Ken nor Akuma made it to the Marvel vs. Capcom 1 roster, but the Red Cyclone did!
Vega is also very popular. He even placed 10th on IGN's Top 25 Street Fighter Characters list.
Cammy was the first of the "New Challengers" to be present in most later games, and the only one other than Akuma to be involved in early crossovers. She even made a cameo in Wreck-It Ralph (Albeit wearing something more modest) along with M. Bison, Chun Li and Zangief.
Not to the extent of Cammy, but Fei Long was the only other "New Challenger" to make it to the console ports of IV. It helps that many players consider him an awesome Bruce Lee Clone.
World Warrior Guile status as a Game Breaker is legendary, to the point that some considered it as one of the most broken fighting game character of all time. In fact, it was considered the same character that invented Touch of Death-esque combo(hit confirm that resulted in a KO) into the genre with his Four Fierce Combo. This, on top of his ussual Flash kick and sonic boom.
Bison's Champion Edition version has deadly priority with most of his attacks, and he has a scissor kick combo that can completely shut down half of the cast. Even when he was nerfed in Hyper Fighting he still had some ridiculous combos.
In Super Turbo and its successor HD Remix, Akuma is banned for having ridiculously overpowered combos and juggles. He was eventually balanced out in later games, with his most balanced form so far being in IV.
Hilarious in Hindsight: In Zangief's ending, Gorbachev claims that Zangief's victory has proved that "the Soviet spirit can overcome all obstacles". Just months after the game came out, the Soviet Union, still under Gorbachev, was dissolved.
One Japanese commercial for Turbo featured a live action Guile duking out against a live action M. Bison. One year later...
Launcher of a Thousand Ships: Out of all the SF characters, Chun-Li has the most fan-made pairings, namely with Ryu, Ken, Guile, Charlie, Cammy, and Juri). While it's not really bad when it comes to most shipping wars, it has caused a bit of varied mileages in the fandom. The Street Fighter anime from the 90s (and to a lesser extent the manga) have helped Ryu, Ken, and Guile in this regard. Though while they are only good friends in the series one of the reasons why Ryu is fairly popular in this regard is that unlike the other 3 men mentioned here Ryu is the only one whose still alive and not Happily Married
Justified in the case of Charlie since the official storyline states that they posed as husband and wife while traveling in search of Bison.
Bison. Why else would a super powerful man get twelve beautiful teenage girls brainwashed into becoming his Bodyguard Babes, huh?
Mexicans Hate T. Hawk. and Japan hates Dee Jay: Although no one seems to be complaining about their inclusion in SSFIV. Probably because all the other great characters they brought in at the same time distracted people from complaining, or maybe because of the Nostalgia Filter from having the entire cast of Super II Turbo back again.
Brazil loves Blanka: Hilariously, Brazilian player adore Blanka and actually are disappointed that he's not a native Brazilian.
Porting Disaster: The Xbox Live Arcade version of Street Fighter II Turbo: Hyper Fighting. The game had serious lag on most stages, even more lag on Balrog's stage, horrible balance, and an infinite timer on the character select screen. That last gaff, when coupled with the ability to de-select your character, led to long times at the character select screen due to counter-picking.
Not the whole game, but the Sega Genesis port of Super II had horrible music. Quite pathetic considering the earlier Special Champion Edition had music that was very faithful to the CPS1 original music.
Unfortunate Implications: The title screen of the original edition of SFII has a white guy punching out a black guy. The hapless punchee got changed to another white guy in the Mega Drive/Genesis exclusive Special Champion Edition and the opening was removed completely for Super Street Fighter II.
Some of the national stereotypes the characters represent (Dee Jay is a dreadlocked Jamaican musician that uses mon in his dialogue, Dhalsim is a magical Yoga Hindu, etc.) haven't aged well over the years to modern audiences. Somewhat mitigated by the fact Capcom, a Japanese company, isn't pulling any punches with itself in the form of Ryu and E. Honda.
Woolseyism: "Vega" is a fairly common Spanish surname, making it somewhat more appropriate for him than the dictatorial Bison. In addition, a "Balrog" is a fictional creature known for being large and monstrous, making it a more fitting name for the ruthless Boxer than for the narcissistic and graceful Claw.