I just did a ton of tube rolling. Theres 14 12ax7s and 8 EL-34s in my full sized rig. Marshall-based circuits.
Its the ultimate YMMV question because a tube can sound great in this circuit but not as great in another, and the interpretation of sound is so subjective anyway.
So with that said, I did form some pretty clear impressions of the differences.
The best power tubes were the big bottle Ruby EL-34-STR. Compared these to: Electro-Harmonix, Svetlanas and JJ EL-34Ls.
The best phase inverter was the Sovtex 12AX7-LPS, only one that really seemed to make a noticeable difference actually.
12AX7s: The Chinese ones in general sound best "upstream" in the first gain stages, they seem to have the most warmth and crunch. The Russian 12AX7s didnt have as much breakup and and werent as rich sounding when used there. The exception was the Sovtek 12AX7-WA which sounded very hot and had tons of breakup and sustain (but was also noisier and had a messy quality that the punchy and clear Chinese tubes didnt. The Russian tubes work great in the stages that drive outputs and effects sends, but for the critical V1 positions the Chinese always sounded best.
Chinese: generic 12AX7 and 12AX7-B, Groove Tubes 12AX7-C
Russian: Sovtek 12AX7-LPS and -WA, Electro Harmonix, JJs
2 x Peavey Rockmaster preamps
2 x Peavey Windsor heads
Going for smooth saturated crunch without any harshness or fizz.