My Favorite of the Angel/Spike books so far has probably been Spike: Old Times, and Spike: Lost and Found. I really thought that they got the voices of the characters, as well as the feel of the Angelverse down quite well. I also very much loved Spike vs Dracula. It was great silly fun. Probably my favorite mini-series thus far. Most of the Angel coics have disappointed me so far. It's a shame too, because Angel is probably my favorite character (tied with Xander), and Spike, well, not so much.
The character spotlights have been good overall though, especially the Wes, Connor and Illyria ones. (Didn't like Spike in the Wes one, but Wes hiself was good enough to make up for it.)
Edit:
Read Asylum too, better than ost Buffyverse comics, but I didn't think it was really all that. Lorne was kinda useless in it, and it felt like an overblown fanfic. Not horrible, just not as good as some have been saying.