Ok here is a theory on tubes, and it is my theory and my opinion, nothing more.
I believe we like things that are out of the norm, that might be harder to obtain. I have been told that Russians do not consider the Melz 1578 that great of a tube, and would rather buy Sylvanias. Americans have a lot of access to Sylvania, RCA, Tung Sol etc. yet here we are looking for specific Russian tubes, or British tubes. Occasionally there are some US made tubes we think the world of but some recent tests are a prime example of my theory.
A friend thought most of the 8 tubes (6sn7 equivalent) I presented him in a blind test sounded similar, then he got to the Melz and it was so different, it stood out to him. He picked it as his favorite. Last Saturday I went through a bunch of Amperex from different periods and most all of them sounded harsh and raspy, I basically just plugged them all in without looking at the types very closely and my favorite was one that probably sounded the least like the others, but I liked the sound. It may have been the cheapest, and least sought after yet, it sounded so different to me, and I was not getting the harshness I disliked in the other tubes, with my amp and DAC setup.
Do I think the overall SQ of single triode tubes is better than some really nice dual triode 6sn7's, doubtful, but they sound different. The spacing is nice. Will a 7n7 rank towards the top in my testing? Or a Foton ribbed plate 1954? Possibly but once again, when you listen to a lot of RCA's and Sylvania's, they sound very different so to me that could be part of it. I like to do blind testing because you can eliminate some of the preformed ideas. That does not mean a tube like a GE would finish toward the top, there are tubes that can be stand out in a bad way.
If you have access to a lot of Brimars, is that your tube of choice if you are British? Just some thoughts, nothing else.