Great amp, loving mine too! I have played with quite a few different tubes on it, and settled on JJ EL84's for the power section, it really tightened up the lows and low mids, added nice body. The stock chinese tubes are actually great if you love scooped mids and high gain, they seem to be naturally scooped and super high output. I did not like JJ 12ax7's in the pre's, more muddy, less definition, too dark and lower gain. Tung-Sol 12ax7's have amazing body in the mids, very clear and defined and similar output to the chinese, but you do SLIGHTLY lose some of the massive breakup the chinese have. If you like metal, keep the chinese, if you enjoy mids, try tungsol.
I did try a 12at7 in the first channel to try to get it more clean, works great in other amps but didnt notices a significant difference that I liked in the JCA22h, instead I just keep the pre-gain at like 1ish, and turn the power up to 6ish on that channel for clean cleans.
Haven't tried EH tubes in it.
Hope that helps some!