jakecanada
Yogiboy is right the highest gain of the 12**7 family is the 12AX7. And they all sound different. My preference is for NOS ones. To give you an idea of my experience of just some of the sound types.
Seimans, Telefunken for analytical monitor type sound.
Mullard Brimar soft'ish big robust type sound.
RCA, GE in-between the above two.
My favorites were nearly always RCA, in all the families of tubes, especially black plate versions of the massive 805 DHT transmission tube.
Cheers George