Your thoughts on these different tubes?..

I'd suggest you try a preamp that uses 6SN7 tubes. It probably will be a more full sound than with a 12AX7 type -generally-, many exceptions. There are still many available and affordable NOS tubes to have fun "rolling". The 6SN7 are just a great tube "family".
Your speaker's efficiency will dictate your power requirements but KT88's/6550's are powerful enough not to limit you too much, allow for tube switching fun and decent bass. (Quicksilver amps are a good value choice here.) I find EL-34's to tend to sound thin in inexpensive amps. Do try EL-84 based amps if you have more efficient speakers. They'll surprise you!

I prefer the EL-34 over the KT-88. In regard to the 6922 as opposed to the 12AU7, although they are two entirely different animals; I like them both. My impression of the 6922 is of a very neutral, high definition tube that can create a 3D soundstage; while a 12AU7 is warm and beautiful, it sounds best with female jazz vocalists.

EL 34 s are the best and most beautiful sounding. The 12ax7 is a very good sounding tube and lasts longer than any of the others and is the easiest to get either on the NOS market or brand new. My humble opinion after 35 years of listening. Shay

In my push-pull amp, I prefer the EL-34's to the KT-88's. I do not find the EL-34's to be bass shy, either, but I think this depends greatly on the amp and the speakers. They are warmer sounding, and do a better job with both vocal and instrumental timbres. I listen to about 90% classical and 10% jazz.

I,ve owned two tube amps recently from the same manufacturer, Rogue. The Stereo 90 uses KT88, and I loved the authority in the bottom end and the headroom of 90 wpc. I have the Atlas now, and the el34 gives a fantastic 3d sound. A beautiful midrange through my Nola Boxers,. The bass is a bit lacking, but I'm using a stand mounted 2 way speaker.