What is your favorite tube type?

My recent faves after trying various types have been the new Tung Sol 7581a, but I recently bought a Dennis Had "hot rod" SEP "high output" (12wpc or something depending on tubes) that's around 6 months newer than my current Had "fire bottle," and it seems to sound best with new Gold Lion KT77s. The "hot rod" has more voltage according to Had, and the internals are nearly identical to the "fire bottle" except for an extra Jensen cap or two...the two amps are VERY similar sounding and I'm not sure yet which one sounds better, and I'm having trouble locating any info on what, exactly, is the technical difference between these two amps...anybody know the answer? 

Love Amperex 6922 or 6dj8 and 12ax7 as well sounds wonderful!!

@ebm  I just picked up a pair of Mazda 1960's vintage halo gutter 7308s.  These things are the bomb!  Just glorious sounding tubes.  Much better than my previous Telefunken E88CCs.  I haven't tried the Amperex 6922s yet.  Generally, I have not been a lover of 6922s, much preferring 6SN7 based designs.  But these Mazdas are something special. 

My two favorites right now are Sofia 6SN7(lush but detailed) and Tung Sol KT150(powerful and airy).

Depends on where the tube sits. My favorite tube of all was a black plate CV5042 (of uncertain heritage) which is a military version of the 12BH7A but it was better than those. It had silent blacks and huge soundstage with exceptional detail in a cathode follower circuit.
I also loved my quad of Marconi-Osram GEC KT88s in a Tim deParavicini power amp. Delicate, tonally colorful midrange and sweet highs. Bass not great but...
Currently, my favorites are the @wolf_garcia mentioned TungSol 7581A which are seamlessly tight and clear and powerful in place of 6L6 and EL34/KT77 and, the PSVANE Globe 6SN7 with its unbelievable detail. It needs a lot of burn