I'm not looking per se. I just like to hear about other people's favorites...especially those who may have heard something outside my envelope of experience.
I like GM70, 14 watts, made by Audio Detail in UK. I also like Thomas Mayer 46, but it will under drive many speakers, unless I ever get to hear a push pull version that sounds close. Some Eimac amps are good for higher power, having heard Silvercore, Trafomatic, and hope to hear NAT with Eimac soon.
SETs is a question of matching drive/grip with the required speaker. This match differs a lot. Usually the higher powered speakers have more grip and lower powered speakers less, but it is less a question of loudness in wattage, rather more of drive matching. Some horns do not want too much grip.
As such, speaker owners should find what zone their match is in. 46, 45, 2a3 is one zone, and 300b singled ended sub 10 watts falls there, while higher powered 300bs usually sound less good but can be nice where more power is required. Then push pulls of 2a3 and 300b in slightly more power. Silvercore 833c (good value for money as relatively inexpensive, but not all out), Lamm, KR fall in the higher powered category, but lesser power than the Eimac ones. GM70 if well made seems to give as much nuance and agility as lower powered tubes but with 211 oomph.
So it requires a bit of matching, tube rolling, driver rolling, then one has to optimize the amp as far as it can go without giving up the voicing, .i.e. get right quality transformers, caps, etc. All this requires some amount of playing around, serendipity, and dig into rabbit hole work.
Triodes aside, Misho's single ended pentode is magic with Altecs with his entire chain, and EL84 push pulls can be great value for money too. There are many other exotic low powered tubes though, 50, AD1, RE 604, so permutations and combinations galore.
In the very high powered category, KR audio circlotron was excellent but not many were made. And their number of tubes and tube cost is too high.
