Suggestions please. Your favorite 3, 12ax7 tubes

Just get the most expensive tubes you can find, chances are they'll have the most effusive recommendations and largest cult following.  After you buy them you'll be able to post back here and find plenty of others that will agree with your purchase and help tamp down any cognitive dissonance.  We got you, go nuts. 

Okay perkadin, will do

Mazda silver plate 12AX7 are my easy favorite. They can be a tad bright, but their dynamics, detail and sweet mids more than make up for it. However avoid the 5751 silver plates - they're a ridiculously bright mess. 

Next is GE 5751 TMBP, specifically the 1953-54 vintage with "silver clips" over the plate ears which poke past the micas. Other GE TMBP vinatges are good but just don't have the magic. They're all better than the RCA TMBP, IMO.

Too many close calls to pick a 3rd, but sure RCA black plates and Telefunkens are in the running. The Telefunken ribbed plates are brighter than smooth plates, but then they're also more detailed and dynamic - just not as good as those Mazda silvers. Ameperex / Holland are always well balanced and should be in the mix. 

Mullards are too thick sounding for me, but a good choice if you need something really warm & syrupy. 

You know, the modern Russian Gold Lions and Tung Sols are quite good too. 

Raytheon 5751 2 mica black plate with windmill getter are the best 12ax7 tubes. Sylvania triple mica black plate 5751 are 2nd. The Sylvanias are warmer, sweeter sounding. But honestly gold lions or psvanes are the best value.