We recently had a discussion where Bill (lbpesq) bought one of the all-in-ones. I forget which, might have been the Zoom, but you should be able to find the thread with a search if he doesn't pop in here. I remember it was able to record four tracks with two mics facing forward and two to the rear. A pretty cool feature for jams where everyone is around the outside of the space.
Personally, I also have a matched pair of Rode NT5 mics that I like for general stereo use. They can generally capture a stereo mix into any decent recorder, or work well on acoustic guitar or as drum overheads if you're trying for something more serious.
The all-in-one box has to be the most convenient, though, if you're not looking for a demo to send to the record company. They also have to be the easiest to set up. Never an excuse that it was too much trouble to get the recording. Also, if it sounds good in the room, it should sound pretty good on the machine. No extra effort, record it and press play.
When I really care about the tone of my bass in one of these situations, I like to use something with at least four tracks so I can dedicate one to a bass DI. That usually involves some amount of mixdown to balance levels, though.
