My favorite 6922 is the Amperex orange label from the 1970s. Pretty easy to find and doesn't cost a fortune. Some of the famous old 6922s are too soft for my taste.
both of the above suggestions will be a big improvement over the stock tubes, also consider siemens, mullards, and telefunken, we tube rolled a number or different pairs through a friends Canary cd player and he decieded on gold pins lorenz (sonic flavor close to that of telefunken ) I personaly liked the siemens
I liked Amperex Bugle Boys (made in Holland)in my 128. Warm natural bass with good extended highs. I've been intending to run some Seimans 7308's but I haven't yet. I would expect from this combo dynamics and bass with mid-range and high end clarity, but at the expense of some warmth. Just a WAG though!
However, I think your choice may be dictated by your associated components more than anything else. I'm using mine with Primaluna stuff and the 6922EH supplied by the manufacturer seem to fit better than the other tubes I've tried (EI's/Teslas NOS/JJ Teslas/6H23EB's/Sovteks and Amperex).
I second the comment about what your associated components are... I have settled on Siemens PCC88 at the moment but am trying Amperex Holland 6922 and NOS Tesla 6922 which both work well for me. I have a hybrid unico SE amp with great warmth and bass slam so the detailed siemens / telefunken german made tubes seems to work best to my ears :-)