12ax7's

I agree with Fletchj and Detlof, it really depends on your taste and the circuit it's used in. The best 12AX7s I've found for my taste in Jadis equipment have been Telefunkens, and the best Tele's I've ever used are their premium E803CCs. Much quieter than the standard 12AX7s, and they last forever.

Much more transparent and dynamic in my JP80 and JA80s than the standard 12AX7s, as well. Obscenely expensive and very rare, but when you want that last bit of refinement they do deliver the goods. Fortunately you get much of their performance from many less costly tubes.