Anything over two minutes that Frank Zappa ever played. But, it's all a qustion of taste - some think that Spice Girls are better than Beethoven. Enjoy, enjoy!
if you google "best guitar solos" you'll find any number of lists, and all of them will be different. but some of the solos that keep cropping up:-
Dave Gilmour - Comfortably Numb
Eddie Van Halen - Eruption
Jimi Hendrix - All Along the Watchtower
Mark Knopfler - Sultans of Swing
Brian May - Bohemian Rhapsody
personally my vote goes to the instrumental break in the Blue Oyser Cult's "don't fear the reaper".
I know the drums are playing in the background, But you can't rule out Lynyrd Skynyrds - Free Bird.
For a true solo, Dave Gilmours - Comfortably Numb would be my choice off the top of my head.
One of my favourites is the instrumental break, by Slash, in Guns 'n Roses Sweet Child of Mine.
I'll probably think of umpteen other favs over the evening, though.
'There is an anecdote out there that describes this as the song in which Neil Young does the second best guitar solo in the history of rock'n'roll, sings a little bit, then does the best guitar solo of all time. I don’t know about being the best solo, but it’s certainly the most incendiary.'
I wouldn't like to say what is the "best", Supernatural is up there of course but there are many stunning performances. Interesting that Radagast is offering Santana, I don't know that one, I was going to suggest this one: