My choice would be the CJ Premier 16LS II.
I’ve owned their ET5 and CT5 and have heard various others from their range, old and new, and there’s something special about the 16LS that the others hint towards but don’t quite reach. It seems to walk the line nicely between having that classic tube bloom/warmth, and having sufficient transparency and clarity. Perhaps the ACT is voiced similarly but I haven’t heard it and it’s quite a bit more expensive.
Others I’ve owned and enjoyed include the Allnic Audio L5000 DHT and a Supratek Chenin. The Supratek lacked in many ways and wasn’t a good choice for my system at the time. The L5000 was excellent and I regret selling it, though it didn’t have the warmth and bloom that it seems you’re looking for, far more neutral. Most of the modern tube preamps I’ve heard are voiced to be more neutral and transparent. The CJ 16LS has that classic tube quality and makes little attempt to hide it.
Good luck.
You beat me to it, good thing I read to the end of the thread, thus far.
The Conrad-Johnson Premier 16LS (1 or 2) could be the perfect fit for what you describe you are looking for. Known as "the baby ART", it uses 6 of the 6DJ8/6922/7308 tube family which makes for a wonderful opportunity to try the many varietes of that tube. I had one of these linestages and wish I'd never sold it.
Here's the link to the owner's manual: