Recommended Phase Inverter 12AT7


I have read that there are a couple of 12AT7  tubes that are the "holy grail" for some guitar amps.

Are there such "highly recommended" 12AT7 phase inverter tubes for audio amps?

If not, what have you had success with?

chinook9
What are you looking to accomplish?  Want it warmer, want more detail or more gain?  To me RCAs are the best in my system but it all is subjective.