Stag's certainly good. In terms of "best", though, there's rarely one that is just flat-out better than the others. It's usually dependent on where you want to use them.
If I had to pick one, though, I suppose it'd either be Psylar or Geomancer.
Psylar, you say? 🤔
Quite a few reasonable options. Deacon, Seeker, Uugo, Geomancer all stick out. Just looking for overall power level, ceiling, ubiquitousness. If I had to settle on a few, I'd go with Uugo or Geo I think. Both champs that got even better with Hydra, too.
Based on my own experience
Royal guard - use in hydra a lot, FK and sometimes DT
Geo - useful in lots of places, use most in hydra i have built 3 of him though so it gives an idea of how much i use him
Vogoth - do not own but annoys the hell out of me.
Deacon - amazing champ
Demytha - Amazing champ and opens up a 1 key UNM option
Overall i was torn between Geo and Demytha, but went for demytha as she was the key to a full auto 1 key UNM.
Given Husk, would you include Royal Guard in that too? Value went way, way up with Hydra.
Yes, but RG went from used by anyone who already had... I still haven't pulled on my main.... ugh
Whereas husk was chickened or vaulted by most prior to hydra, despite a pretty awesome kit on a HP champ.
I need to amend my comment about vogoth being only ive built 3 of, I 60d 3rd husk a few weeks ago for hydra... lol
Geomancer. I dont have him yet but he is my most wanted champ. Even higher than some legendarys. My second pick is Stag Knight (who i also dont have), Rector Drath (again, dont have) or DoomPriest (also dont have).
I think DP is a very strong second, and, arguably, even better than Geo. I would definitely rank her well ahead of Stag, and easily ahead of Drath too.