I have had a Quickie for five months (now with the PJCCS) and have tried a bunch of different tubes. I have at least 40 total and they were thoroughly tested before I bought them. I am running it right now with a CD player >Quickie>Fisher SA100>Fostex FF165K Horns with Gallo TR1 powered sub crossed around 80hz.
All of them are microphonic, but some more than others. However, none of them really howl or squeal like it would in a guitar amp (and I have had some squealers in my Marshall combo). I did pickup some Herbie's dampers and I think they help a little. I have come to believe that there is no huge difference between microphonics and manufacturer because they all have them, but maybe the RCA have a little less than others. I may even get the guitar amp dampers from Herbie's and add those so both tubes have two dampers each.
RCA 1940's - very well defined bass, clear mids and silky treble, one of the most balanced tubes; wide soundstage. Microphonics 3 out 10.
Raytheon VT-174 - similar bass and mids, smooth treble with a tiny bit of roll off; warmest tube, liquid, Very wide soundstage. Micro 5/10
Tung Sol - 1950's - huge bass, subdued mids and tons of treble but slightly edgy; average soundstage. Microphonics 6/10
RCA 1960's - Strong bass (more than Ray, less than TS), clear mids, very nice treble (less than TS, more than Ray) Very liquid; average soundstage. Microphonics 4/10
Sylvania 1950's - nice clear bass and low mids, liquid mid and highs, a very sweet sound; wide soundstage. Microphonics 6/10
Sylvania 1960's - didn't get to these yet, will update when or if I try them.
GE - deep bass and plenty of treble like the 50's Tung Sol but with better midrange, a very wide frequency range; a little smeared overall compared to the Sylvania. Very wide soundstage. Microphonics 5/10
Tung Sol 1960's - deep bass, improved midrange and sweeter treble than 50's and overall smoother without the edge; average soundstage. Microphonics 6/10 (an improvement over the 50's TS)
Right now I like the RCA's and Raytheon the best with the 50's Sylvania and 60's Tung Sol next.
I still am not sure if there were any actually made in Europe. If there are, I would like to try them. Cheers!