Steve Howe of YES and ASIA is hands down my favorite guitarist. He puts on a kick-ass one man show. Look up 'night of the guitars' on Youtube. There were a lot of greats on that tour, including Howe. He perfomes a great track called 'Sharp on Attack'. If I had to pick solos, it would probably be 'Sound Chaser' or 'Wurm' (from Starship Trooper). Some of the coolest stuff he did, in my opinion, is what he does behind the vocals, bass, keyboards, and all the stuff they had going on in the body of their songs. 'And you and I' 'Topographic Oceans' come to mind. other favorite axemen would be Steve Hacket (Genesis), David Gilmour, Joe Satriani
Here's one I like http://www.youtube.com/watch?v=4bQocD_kxJk Wet Sand by Red hot chilli peppers, listen from 3:40 on for guitar solo at end.
This thread needs to be resurrected as we've only scratched the surface. Jeff Beck's work throughout "People Get Ready": you want soul, you got soul! http://www.youtube.com/watch?v=zO12vZpeITY
...don't know if it's been mentioned, but Dickey Betts' solo in The Fillmore version of "Stormy Monday" might be the best blues solo I've ever heard. http://www.youtube.com/watch?v=B-mx63tN7Qg It's hard to believe they were all in their early twenty's. That performance has a maturity FAR beyond their years.
http://www.youtube.com/watch?v=8KUSkGeaUPU I'm usually an old school guy but Vai is as expressive as any blues player and utilizes modern techniques. No need to shred here, just making it pretty w/o showing off. Note the scalloped frets. Check out the solo on Mountain Climbing from Theme for an Imaginary Western, studio version only. Again, no need to shred just exemplary note selection and ends with a harmonic whistle-- and tone that West if famous for.