Best 12AU7?

I can also vouch for Radiotechique. I am running the equivalent version produced for the French military, the 6189/12au7 in my Rogue ST100 and I would describe the sound as "Lush".

+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.