Best 12AU7?

+1 on contacting Brent Jessee.

I have NOS RCA clear tops and black plates. The clear tops are brighter up top, but the black plates don't lack for treble extension and overall I prefer the balance of the black plates. Good luck with your search.

I asked for similar (not exact) recommendation from Brent Jesse and was recommended the Mazda Grey ladder ribbed. Been super happy with these.

Brent Jessee - 12AU7 in stock

I’m currently trying the Gold Lion gold pin (new) in my pre-amp.  previously had JJs 802’s.  The preamp is a VTL 6.5 and so far, can’t really tell the difference.  Have to burn them in for longer.

My favorite 12AU7 has been the French CIFTE from the early to mid 60's. 

They have gotten expensive and tough to find.

If you are using this in the buffer stage you recently posted about I would not drop a lot of coin into tube rolling.

Maybe try an RCA clear top as they are clean sounding and cheap as chips to see if it makes much of a difference.

I use expensive vintage tubes in my inexpensive kit gear, but in gain and driver stages.

DeKay