I love my Marshall AS50D for the price that I bought it used, but so much of this choice depends on what features you want and how you will use the amp.
If I were buying new and playing out, I would hold out for an SR Jam 100. They are the most natural sounding acoustic amps I have ever heard, have thee channels, loads of inputs and come with an onboard mixer so you can go to a House PA. They also have come way down in price this year.
The SR also sounds pretty good with arch tops and semi-hollow/hollow body electrics.