Santana's tone is a favorite of mine, especially on the early records ("Black Magic Woman", for example- it's the mixture of bite and sustain, and the impression that the guitar's "talking"...). I'm also a fan of David Gilmour. Both his signature atmospheric yet biting solo tone and the variety of interesting textures he uses on rhythm parts and fills. Well-used effects are... well, well-used.
On a different note, the classic Hendrix and Cream tones are... well, classic. Love me some 60s/early 70s fuzztones, and it works very well with the riffing style. Also, Tommy Iommi. YES.
And, for something completely different, the tones Sonic Youth get out of their guitars. Both guitarists. So abrasive, yet hypnotic, and once again, it works VERY well with the playing style.
There are several guitar styles I like.
Keith Urban usually has very good tone. His solos still have discernible notes and melodies, instead of just being lightning-fast runs like Brad Paisley, and there's a lot of passion in the way he plays.
I also like the "chicken pickin'" style that Jerry Reed used. Session guitarist Brent Mason plays a slower "chicken pickin'" style a lot, too.
Pete Anderson also had a pretty "fat" style that still somehow sounded country. You can hear him on almost everything Dwight Yoakam put out before 2005.
And if you want some great early fuzz work, check out "Don't Worry" by Marty Robbins. That was entirely unintentional due to a faulty preamp.
edited 20th Apr '14 5:17:04 AM by Twentington
My favorite would have to be the tone that George Harrison used on his guitar-playing a lot. Best examples I can think of are in "You Never Give Me Your Money" (about 2:48 in)
and on Cream's "Badge" (about a minute in)
.
Although it's not quite the same, I believe Electric Light Orchestra used a similar tone on the guitars on their song "10538 Overture" (the very beginning onward)
and The Pillows also use a similar tone in the chorus(?) of their song "STALKER" (again, about a minute in)
.
I'm not sure what this is called, but I love the reverb effect that Bo Diddley achieved
.
Also heard on Robert Plant & Alison Krauss's version of "Rich Woman"
(I think T-Bone Burnett is the one actually playing the guitar).
Sonic Youth have used many guitar tones, nearly all of them fantastic, although that is just as much a matter of what they are playing and the techniques used therein matching the timbres used as the timbres themselves. Ditto Wire, particularly circa Chairs Missing and 154.
For pure corrosive evil, Richard Kirk's early work with Cabaret Voltaire has a delightfully nasty tone, or noise rock acts like The Goslings whose distortion could take paint off of walls and burn holes in the floor. Pure galling noise-tones are always delicious. Take the ocean feedback washes on The Birthday Party's "The Friend Catcher".
For most out-there tones, St. Vincent is always a good call, not unlike early Wire. Her guitar may sound like anything and everything. Very weird and expressive.
And then there's that broken glass clarity of the flange effect and carbon composite fretboard on Keith Levene's Public Image Ltd. work that is simply to die for. And whither Bernard Sumner's inimitable scrap-metal-glint snarl on Joy Division tracks like "Ice Age" or the off-key lullaby chiming of "Ceremony" and "Disorder"?
I'll hide your name inside a word and paint your eyes with false perception.Very eloquent points made here, actually. How'd I miss Wire, The Cabs (though I'm more familiar with their later EBM records like The Crackdown and Micro-Phonies, I do like the early stuff), The Birthday Party, Keith Levene and Bernard Sumner?!
Also, I'm a big fan of Robert Smith. He's more well-known as a singer, but I always thought The Cure had a cool-sounding guitar tone- sorta a Goth/Surf/Psychedelic Rock thing happening. He also recorded with Siouxsie And The Banshees.
Who had a long string of great guitarists. And Daniel Ash's signature noisy-but-atmospheric stuff in Bauhaus is pretty sweet, too...
Also, of course, there's Bob Mould's tone on the various Husker Du albums, Peter Buck's work in REM, Paul Westerberg's ragged rhythm work in The Replacements and, of course, Curt Kirkwood's kaleidoscopic variety of tones (alternately jangly, trippily weird and abrasively aggressive)on the Meat Puppets key albums.
I love many different styles of guitar playing and tones...
edited 21st Apr '14 12:30:50 AM by sharkcrap11

Exactly What It Says on the Tin. Sure, I could make "Your Favorite Signature Sound," but that would be too general for my liking.
I think Jerry Cantrell needs little introduction, but even still I can't praise his sound enough. Man in the Box, What The Hell Have I, No Excuses, Heaven Beside You, and even newer songs like A Looking View should say enough about him. He creates atmosphere like nobody's business.
edited 19th Apr '14 11:45:28 PM by Alucard