A range of different guitarists (silly to say one is the best):
All Along The Watchtower - Jimi Hendrix (yes there are many other Hendrix solos just as good... I just find this the most perfect in its structure & tone (drool) )
Red House - Hendrix (beautiful, perfect note choice)
Star Spangled Banner - Hendrix (If this wasn't THE MOST definitively kick arse moment in guitar soloing I don't know what is...)
Voodoo Child (slight return) - Hendrix (another reason why he'll never be topped)
Crossroads - Eric Clapton (Cream era - best solo Clappo ever did bar none)
Layla - Clappo
For The Love Of God - Steve Vai (amazing!

)
Whispering A Prayer - Vai (an absolute modern classic)
Tender Surrender - Vai
BTW - Vai kicks Eddie Van Halen's arse clean across the stage, in every way (taste, technique, style, musicianship, intelligence, ego (or comparitive lack thereof), showmanship, etc). Eruption would be absolutely
nothing for Vai to pull off, if he cared.
Comfortably Numb - David Gilmour (Pink Floyd) ... nothing need be said.
Money - Gilmour
Sultans Of Swing - Mark Knopfler (Dire Straits)
Going Home (theme from Local Hero) - Knopfler
Brothers In Arms - Knopfler
Texas Flood - Stevie Ray Vaughan
Little Wing (possibly EVEN more beautiful than the original IMO - and thats saying a LOT!) - SRV
Scuttlebuttin' - SRV
Cliffs Of Dover - Eric Johnson
Desert Rose - Eric Johnson
Scatterbrain - Jeff Beck (defined Jazz-Rock)
Cause We've Ended As Lovers - Jeff Beck
Just about anything from these guitarists will be amazing solo - wise. There's probably something super important that I love that I've forgotten... Oh well!
EVH doesn't do anything for me (strangely). I like his tone on "Panama", but thats it. He's not a genius.
Jimmy Page doesn't do anything for me (strangely). I like the bluesy riffing on "Whole Lotta Love" and "Heartbreaker", but Stairway leaves me as a cold lump of festering cheese I'm sorry to say...
Slash doesn't do anything for me (strangely). I somewhat like "Sweet Child O' Mine" but thats it.
Weird huh?