NOS Tubes for Rogue Tempest II

Looking for some suggestions replacing the stock tubes. I want a little more transparency or pop yet retaining overall smoothness and good bass. I want to start with the 12AX7's and the 6SN7's first. I was told the Sylvania 6SN7 GTB would be a good one but there are several versions so I am a little confused. Also the same with the 12AX7 what is a good value without breaking the bank.