its going to be tough to say because everyone will have a different opinion and Im pretty sure that most guys including myself have not tried all the attenutors that you have listed.
Well for Marshall based amps , I like the THD hotplate and the Marshall Powerbrake.
I know the powerbrake gets a bad rap at times but they work really well with marshall type amps.
The THD is pretty much industry standard these days and I think they work really well. (Ed degenaro can fill you in on them being that he works for THD!!)
I also liked some of the Weber Mass clips that I heard. The mass seems to work really well and it wont break the bank plus it can handle multiple impeadances.
I also dug the Bad Cat Leash clips.
All in all, I think that its going to be pretty hard to get a bad attenuator these days!!
I have tried a few. I like my Hot Plate. With some amps it does not do much tone wise. Other amps it seems the only way to go. Try it with your rig to see if it does what you want. You well need to re-EQ a little.
I've always gone with the THD in the past. Never tried the others. I've heard raves about the Richter, but they are notoriously hard to get. Supposed to be a new version coming out, but who knows when. The Ultimate has also gotten good reviews for tone, if you can handle the whole 30 ohm load into a solid state amplifier thing.
I've got a THD, never tried any others. It's great on the -4 and -8 settings with the treble/bass compensator off, but at -12 and -16 you have to use the EQ adjustment thing. I really, really like it, but I don't have experience with competing products for comparison.