I find Marshalls to have hella better distortion than Fenders or Ibanez amps. I prefer Fender's clean tone over Marshall's, but I use my distorted channel more than my clean, so I would go with the Marshall personally.

I myself own a Peavey KB/A. What?! I have a keyboard/acoustic amp? Yup, that's right. I originally bought it to amplify my keyboard, but I tried playing my guitar through it, and it sounds great. Not alone, mind you. There's no built in distortion (it's an acoustic amp). I go from my guitar to my RP200 multi-effects pedal, then to the amp. This is a great combo. I can get killer distortion through the RP200 as well as excellent frequency response all around the board from the amp (it's designed for keyboard, which go both lower and higher than guitars normally do). Now that's a badass combo (and it's loud enough to play a small auditorium (~700 people).