And though it's not actually a solo as much as it is a "lead riff" I vote for the guitar part in Burzum's "Det Som En Gang Var" that comes in just under 8 mins into the song.
Also, speaking of Burzum, the similiar 'lead riff' that pops in at 4:03 on 'Ea, Lord of the Deeps. That is quite beautiful.
Also, the 2:45 'I am the loving darkness' solo on Cryptic Wintermoon's 'Supersatan' is really quite lovely, in my mind. On a similiar note, the solo in Illnath's 'Cast Into Fields of Evil Pleasure' (the shortish one that comes right after 'Bending the borders of emotional measure, Cast, far into the fields of eeevil pleeeeasuuuuure!" hit's a really good note.
I'd agree with Robbo on 'Comfortably Numb' definitely. There's so many to think about though, and emotional means different things to different people. I'm a huge fan of those really uplifting power metal and classic MDM solos, for example.