Comfortably Numb live and studio are essentially the same, no? Gilmour didn't improvise much with the latter era Floyd stuff. But yeah, CN has to be in any discussion like this. Hendrix's Watchtower solo. SRV's Life Without You solo was always great. Slash's second solo in Sweet Child O Mine is fantastic. As much as I love me some Izzy, Slash's emotive playing was probably the most integral component of the x-factor in that band. Always love Ira's freakouts in Yo La Tengo's We're An American Band. Lifeson's solo in Limelight is a work of art. I remember being blown away by one of the Machine Guns on the Band of Gypsies Fillmore release.
It's not even close to the same. Check out the one on the Pulse DVD for a great example.
Also

at people bringing Pearl Jam into this discussion.
Are you a musician and or guitarist?
If you are and can't appreciate some of McCready's great guitar work on Ten and Temple of the Dog....you have me scratching my head a little.
But he most certainly is in a discussion as one hell of a gutarist. Guitar driven rock music was still going strong for a lot of us well through the 90's.......and even today with some great bands still around (Porcupine Tree, Muse, Dream Theatre). Early Pearl Jam (first two albums to be exact) and Temple of the Dog has some incredible, emotive, ripping, grooving guitar work.
Fantastic stuff.