I like also like Aldiko, but not the new version. The new version is not as stable on my Android 3.1 device as my as the older version. I also like the GUI in the old version. I am glad I saved a copy of the apk for the old version, and I don't let market update it no matter what.
It also has some nice formatting options that let me see the pages how I like them to be laid out.
The only thing I wish it had is a true "book" look layout with animated page turns. That would be perfect. I guess that is a quirk of mine, but I do like to have it in an e-reader.
Mantano is also a nice reader. The developers are making steady progress and updates on it and seem to be listening to their customers.
Also surprisingly, I like the Nook reader apk. It does not have the formatting options that Aldiko has, but it does have a true "book" layout with animated page turns that I like.