There's been like a billion threads on this in two different forums :lol:
Tung Sol is a good all around tone tube or a module V2 tube for certain mods. They make one of the best 5881 power tubes on the market, truest to the tone of the originals. Maybe not as durable as Sovteks though.
Shuguang pres are a must for any Marshall voiced module (might like a Tung Sol int eh V2 with this in the module V1 possibly for a quieter signal, haven't tried it though).
JAN Phillips 5751 is the RM100 user's friend in the PI, because of the fact that it's durable and cleans up the signal some before hitting the power tubes.
JJ tubes, the stock ones in most MTS amps are great themselves, especially their power tubes.
Ruby tubes are generally hard to go wrong with.
Sovteks should generally be avoided, aside from their 5751 preamp tubes (I think) and their 5881 power tubes (some of the best and most durable out there). I believe Mesa/boogie rebrands some of the nicer Sovteks as their own, and the high quality Mesa 12AX7's are great in Mesa voiced module V1's to help nail that sound.
Electro Harmonix is between the JJ and Tung Sol with their preamp tubes, being a bit noiser; warmth akin to the JJ, but with a brighter top end that adds just enough sizzle to the uber high gain modules, clang to the upper mids of an SL+JCM800, and more chime in clean modules when in the PI or amp's V1. Their EL34s are supposed to be nice, too.
NOS tubes in general are amazing. The Ei 7025's, if you can find them can be either bloody amazing or completely terrible though. The QC on them was erratic, but if you find a good one you'll probably play it til it burns to a fine white powder in your amp :lol:
