I had got a loaner JC2 a few years ago. Unfortunately there was an issue with it and so I cannot comment on it's true colors.
But I have the Rhumba 1.3 with my Parasound A21 amplifier and love what it does in my system. I have shared my thoughts on this preamp on multiple threads here. You can check out the Rhumba pics on my system page.
Have not tried the other brands you have mentioned - so cannot comment.