Save yourself some time....... save a little more money and buy a used EL34 Bogner Shiva. The cleans in the Shiva are as good as it gets. The drive is also pretty impressive.
If you buy an older model it will require you to make a speicial cable for the effects loop. The way I use mine is I have a Boss DD3 & CE2 running into the loop, I have a modded TS9 running straight in (I use this wil the clean channel only). and I have a wah and my tuner. Pretty much a done deal. Great variety of tones and sounds. I paid 1500 for my Shiva 1 12" combo. The heads will be less.
I have played the Genz-Benz El Diablo and did not like the medium or higher gain tones at all, not very defined and just kind of generic sounding.
Meh... I've got one in my garage and I've recorded another band that had one - no matter what I do with the thing, I can't get it to sound good. It's way loud, ruanchy, just sounds dirty to me.
I've heard the JSX, and thought it was too buzzy and XXX-y when dirty and too hard sounding when clean.
The Legacy's cleans are nothing special, but the overdrive channel can sound good with the right valves.
I like the Supersonic for everything except very high gain, where it sounds a bit Mark-era boogie to me. However some people really dig that. Great crunch and clean amp.
The Express is a very cool amp, and probably my pick out of the ones you mention. Go for that if you need something straight away.
But I'm also of the opinion that you should save up to the 1500 mark and get something like a used Bogner, or perhaps a used Mesa Roadster.