I have some experience with the 12AX7 from Psvane. I would definitely give them the nod over all current production tubes that I've tried, except the Gold Lion. The GL gets the nod for tighter, more tuneful bass.
I would not put either brand ahead of a quality, tested, NOS Mullard, Amperex Bugle Boy, Siemens, or Telefunken in sound quality. As with all things audio related, this is a subjective statement. There are other NOS than can be quite good, of course, but those are the biggies. They all have a sometimes subtle, but definite and unique sound character. The different brands will excel in different equipment and systems, and based on listener preference, of course.
I'm not surprised that you are digging the Amperex tubes, as that is one heck of a 12AX7... plenty of detail and the tube black magic, and a nice match with a neutral-to-cool sounding amp. If still running the Belles, I would expect many to lean toward the Siemens or Telefunken. All just generalizations and personal preferences on my part, of course.
If you can afford to keep both, do it. You may decide to make a power amp change down the road, and those NOS Telefunken tubes could come in handy... they're not going to go down in cost in the future. I could kick myself when I think of the NOS tubes I've sold along with gear over the years.
