trivema,
I am pretty much in agreement on your assessment of 12AX7 tubes. I currently run extremely expensive Telefunken ECC803S (the real deal) tubes in my phono stage. It is a very dynamic and vivid tube, but, it is not for someone looking for a lot of warmth. I like other Telefunken variants too. I am also a big fan of the Amperex Bugle Boys; to me, they are warmer sounding than Telefunkens, but, they remain clear and reasonably dynamic. I too don't particularly like Mullards. In addition to being a bit "blah" sounding, in some applications they sound a bit "strange" (sort of phasey sounding).
I don't really do tube rolling myself, but, I heard a few types when first choosing tubes for my phono stage and in other people's system. I even tried some 5751s which sounded quite good, although I actually need as much gain as I can get so 12AX7s are a better match. A friend brought around a big selection of the better tubes he had for me to try. I liked the Telefunken smooth plates, which is why I went all in on getting the ECC803S when I could do it.