As I mentioned earlier in this thread, my most-used expansion pack is the Jamcussion percussion library. Multiple tambourine and shaker types, close and far miked, plus the usual suspects: congas, bongos, cowbells (3 kinds), woodblocks, triangles, and a few exotic world instruments.
I had to look and see which other kits I had, since I've not used them in a while. I've got stuff in there I've never used, like the electronic kit. Brush kit, yeh, that's one I've used. And the BonzoPak.