The TAD red base EL34 sound great, I bought a set of Mesa STR446 and ran them in the Badlander. Nice tube. I went back to the stock STR447 since I run two BADs in my rig. Will use the STR446 when I get my hands on a second quad.
TAD red base 6L6GC Mesa STR448, love these in the JP2C, almost as good if not better than the STR415. I am exploring their use with the Mark VII but only one pair in the class A/B sockets, the other pair in the class A are the stock tube STR445.
I do not own any amps that use the EL-84 so no comment. Also have not tried the 12AX7 or the 7025. These tubes are sourced from Psvane tube company in China. Some of the people from Shuguang are not with Psvane. Some of the others formed a new company. Linlai tubes. not sure what has happened since the Shuguang fire.