Best 6SN7 for the money?

Tube rolling on my Sonic Frontiers was enough to drive me insane with all the 6DJ8/6922 available out there. I now acquired a BAT VK-150 which uses 8 6SN7 per amp (16 total) and I can't possibly roll them all without going broke.

I have read on Agon discussion forum in the past the two front most tubes are more critical, that still leaves me 4 tubes to roll. I also read about Sylvania 6SN7 being a good NOS for the money, but there are so many different Sylvania out there and I don't know the difference.

So I am turning to the experienced Agon members to tell me which 6SN7 to go for, say about $20 to $30 a piece (or $50 to $60 per match pair). BAT owners, should I waste time and money and swap out other 6SN7 with something slightly better?

Thanks in advance.