Here's a controversial opinion: 95% of The Smashing Pumpkins outtakes and demos from Pisces Iscariot, Judas O, Aeroplane boxset, and bonus CDs from recent re-releases are boring or just plain bad. There are some good tracks, of course, which can fill a single CD, but overall there's too much filler.
Machina II, on the other hand, has the best non-album stuff. Maybe it has something to do with the fact that it was originally planned as a proper album release.