I have an SVT and GT200 as my main amps and a TH500 as a backup. While the TH500 sounds good clean I was extremely disappointed with it's overdriven tone. Completely unuseable for me which was a surprise especially considering all the praise it gets for being tube-like. I also owned a mesa walkabout and I found it much more tubey than the TH500. having said that I keep the TH500 around because it has a nice clean sound, small and light. Perfect for a backup amp but it's no substitute for a real tube amp....sorry aggie lovers but it's true.
Lovin my Fender Super Bassman. It's thick and rich with tubey goodness. Although I have 2 others this Fender is my first choice.