I'm using a Fender Super Reverb for clean and a Marshall JCM8000 2204 for dirty. It's a lot to carry but works well!! I do have a C7 Matamp too that I can use if I want to have a third sound with an A/B/C pedal.
I've had to get some Ebtech hum elliminators in to kill ground loops, and a good A/B/C switch - I use the Lehle box, 1@3 I think!!
What I take depends on the gig, if it's just overdrive I'll use two Marshalls controled from the volume pot with an SD1 as a boost. If I need a blues tone the C7 is great, or the Super Reverb for cleans with a TS9 for blues leads.
I'm lucky to have got most of these amps really cheap, if I had to choose one I'd probably go with a Matamp 1224, you can run it on one valve or two valves class A, and 2 or 4 valves in Class AB. Best of both worlds!! (or at least it was before Mesa stole the idea and tried to patent it!!)