One word. Gish. Billy Corgan's recent solo album isn't half bad either -
Walking Shade is probably the best thing he's written since
Bullet With Butterfly Wings.
The Pumpkins' back catalogue contains a fair amount of filler, but there are some great things in there too.
Melon Collie has some beautiful pieces, and I actually like (the first half of)
Machina, though I think I'm pretty much alone on that one