Most definitely what ever you do, stay away from the Ibenhad amps (that's right, I said Ibenhad)...

Out of the 3 you said, the Marshall is probably the best for the buck...
I am going to throw one more amp at you though, well worth absolutely every penny....

http://www.line6.com/spiderII/home.asp

Check out the Spider II amps, starting at $299. YOU can have both the Fender and Marshall in that one, because it is a modeler with tons of tones. I personally favor tube amps myself, but if I were going to buy a new amp, this is the one I would buy. Very affordable at that price also...