Which brand of 45 tubes do you use?

I prefer NOS 45 tubes for my 45 SET mono blocks. I have a few pair of National Union tubes which always sound lovely. I also have a couple of pairs of Philcos that I haven't used.

I haven't tried EML or Sophia because the NOS tubes sound great, are still fairly available (bottles, not globes) and NOS is still relatively inexpensive if you shop around. I simply refuse to pay the prices asked for new triode power tubes. It's a hobby, not an addiction.

Give Andy at vintage tube services a ring. He listens to a bunch of nos 45s and has a healthy inventory. To me not a lot of difference between shoulder types that measure well. And they are not ridiculous expensive. The globes are certainly excellent but at a cost. I have not heard the new production 45 but not opposed. I’ve heard some really good new production like the Shuguang WE6SN7.

Look at the recent posting under chakster and you will see the answers to your question.
Some will depend on your amplifier but in general NOS are more musical under audiophile definition and much more economical.