off the top of my head i'd have to say "Dont Fear the Reaper" by Blue Oyster Cult or the whole song "Cliffs of Dover" by Eric Johnson
I think the simply guitar vibes of old Black Sabbath and the great stuff of Richie Blackmore's Rainbow are high in my favourites. Also some Deep Purple songs are fantastic, Highway star is also great. But I think I'd go from this songs with All along the watchtower or Comfortably numb.
Classic. But I would have to say it would be the transition from the insanity on the electric guitar to the pedal slide guitar in the middle of Gates of Delerium. Or maybe even the end of Ritual.
And by the way, all of the people on this list together couldnt put the amount of emotion into music that Steve Howe can. Maybe Eric Clapton, but Steve smokes him on bluegrass, although he doesnt play blues so everyone besides him.
I'm gonna have to go with all along the watchtower. the intro is great, the first solo is better, and the second solo is simply incredible. this is simply a very powerful song