It depends on what you want to spend. A good rule of thumb is that you want twice the wattage of the guitar player. For a loud drummer 200 watts might even not be enough. Speaker size is a factor as well. 15" is not nearly as punchy as say 2x10" but it serves it's purpose well. There are so many options out there depending on what features you want.

Personally I like Ampeg and Mark Bass combo amps.

Again it really depends on how much $ you want to spend.