Alex Lifeson from Rush on the Album Exit.. stage left. Check out the first solo from Xanadu, he uses volume swells to cut out the pick sound (violining is a name commonly given to this) and give a brilliant brooding overdrive from the low notes with a nice hall reverb. Then he violins some really clear natural harmonics. It lasts about a minute and should go on for ever.
The best solo I've ever heard by anyone is probably the middle solo on La Villa Strangiato, he does the violining again, plenty of soulful bending, shrieking pinch harmonics and blinding speed runs and tuneful but irregular and inventive phrasing.
This guys tone has always been awesome but sadly his solos rarely demonstrate his remarkable talent these days.
There's an (inconsistantly) brilliant guitarist called Terje Rypdal from Norway who shares Lifeson's glacial violining and melodic prowess and plays under the ECM label. Most of his stuff is mediocre but some is exquisite.
In my opinion the most consistently excellent guitarist ever is Joe Satriani, check out the forgotten II, Rubina, Echo etc.. Whooah!
If I couldn't laugh at myself how could I laugh at someone less ridiculous?