I haven't listened to them all, so I'm also using this as a guide for which ones to acquire next.

Here are the ones I really like:
From Boy: The only of the new ones I've heard is Saturday Night, which is an awesome song!
From War: Angels Too Tied to the Ground was pretty good, it would've gone well on the album itself.
From The Unforgettable Fire: Both Yoshino Blossom and Disappearing Act are really good, but I think the punky instrumental Yoshino Blossom might edge it out as the better of the two.
From The Joshua Tree: Wave of Sorrow (Birdland) is great, a very Joshua Tree feeling song. Desert of Our Love is a fun, unpolished little snapshot, better than a couple of the b-sides that were released back then.
From Achtung Baby: Blow Your House Down is great, but I don't know how well it would've sat with the other songs that made the record, so it might be best that it's left off.
Those are my thoughts on the ones I've heard. What does the rest of u2start think?