Depends on how loud you rehearse I guess. I play direct to the house for live performances so I don't usually drag an amp to rehearsals but when I'm jamming with friends (usually in a trio setting) I use an Ampeg BA112. Probably wouldn't be enough live for anything larger than a coffee shop. When I was trying amps at my local shop it was the smallest amp they had that produced what I considered a full tone. With a single speaker, anything smaller than 10" just doesn't seem to do much for me. With a full band or if you use it play live a lot, you'll probably want something with more output though.
Actually, I’m not concerned about gigs right now. I haven’t played gigs with my current band and when I did, in the past, I usually had P.A. support.
I’m a long time Ampeg SVT user, but I don’t carry the 8x10 anymore.
I have a TC Electronic BG250, 1x15 combo, but I’m totally satisfied with it. I’d like more punch, and at least as much portability. So that’s why I’m asking about small amps right now. The TC is loud enough with the master volume set at 3.5.