The Studio T is by far the dryest SE 2A3 amp that I’ve ever heard (I own one), it has twice the power output of the DNA amps (parallel output tubes), and lower output impedance for the same reason.
I haven’t spent enough time with a Stellaris to make definitive statements about resolution, and stage, but given the similarities in tubes, and topology, they are quite different, I would bet that you’d find people who prefer one over the other, and I think if you were to poll them, you’d probably get more who appreciate the presentation of the DNA. Having said that, I don’t think that’s indicative of better, the Studio T. Is faster and more dynamic and has better driver control than the DNA amps, but has little to no romance in the sound. I happen to like that, but it’s not for everyone.
It’s a pointless comparison though, there are less Studio T’s in existence than there are Stellaris at this point, and the odds of you ever seeing one for sale is small, I think I’ve seen 2 in the last 5 years and I bought one of those.