Ok now that is an impossible challenge, for there is a guitar solo for all moods and styles of music. Now to dissect a solo, void of its context, or solo with context of the song makes a difference....hmmm?
I will say Stevie Ray Vaughan's version of Little Wing, #1. I call the whole song a solo, since it is instrumental.
Although short, but highly effective...Mark Knopfler in Sultans of Swing...technical and tasteful.
I would have to agree Eddie Van Halen would have to be in the top 3....Although I have to go with the whole song thing again and say "Eruption" as it essential EVH and set in stone everything he was.
Now to leave out guitar work of guys like, Eric Johnson, Joe Satriani, Duanne Allman, Slash, is a hard thing to do