I have a number of 2a3 tubes, including Sophia Electrics from quite a few years back, Shuguang, JJs, and both Emission Labs meshplates and Emission Labs solid plates. I like the Emission Labs meshplates the most, followed by the solid plates. The meshplates have a very rich, full bodied sound and throw a very large, enveloping soundstage. The sound is, however, a bit phasey sounding (sort of psychedelic). The solid plates do not quite sound as enveloping, but, they are pretty big sounding too.
My meshplates now measure not very good, but, they gave me three years of service, so I can't complain. I've tried them in friend's amps (I use them in Audionote Kagekis) and they did not work in an amp that was set at a pretty conservatively, in terms of bias. Some other operating parameter was out of the tube's range (plate voltage?). The tube started to sputter and then the plates started to flash. I mention this because there are issues concerning reliability of these tubes. My own experience is that they are very reliable when operated conservatively, but they may not be suited for all amps. If you are considering these tubes, I would talk to George Lenz at TubesUSA. He is very helpful and honest in his advice.
I should say that "favorites" have a lot to do with system matching. I probably would have different favorites with a different pair of speakers, or even different input/driver tubes. The other tubes sound pretty good to me also. I really haven't shot out these tubes in any meaningful way, so, all I can say is that the Sophias are also pretty good, as well as the JJs. I prefer all of them to the NOS RCA biplates that came with my amp.
