I'm sure there will be lots of advice concerning brand names. Personally, I like Carvin stuff. The price is right, and they perform admirably.
One thing I think you should look for regardless of what you end up buying is the speaker. I have a 100W single ten inch combo, that is ridiculously under powered. 100W through a 4x10 cab is plenty loud, but that single ten inch speaker just doesn't cut it. An extension cab would probably make a world of difference, but it's already at 4 ohms, and can't go lower. That's my bedroom amp.
I have a 600W 15" combo that has plenty of volume and will go down to 2 ohms if I need to add an extension cab to get even more volume. That's the one I use onstage for monitor purposes.
My .02; Get something with plenty of power, and the ability to add more speakers if you need to.