Short answer: limit
Long answer:
Limit Holdem is the absolute essence of poker and I would prefer it but I cannot see it played anywhere. Neither Limit, nor Pot Limit. So it's kind of strange to even think about it now. Many years ago, when I was really young, it was a thing and I really enjoyed it. However I have not played it in over a decade.
Other games are best limited in my opinion as otherwise it would be pure
gambling. Variance is more prominent in other
poker games and I am an advocate for limit or at least pot limit games.
One last thing, because of the "limit", the microstakes used to be the softest games in existence as recs or gamblers would not care about the few pennies or cents they'd put in the pot and cross their fingers they're hand was best at showdown, I imagine, even queen high, while I was counting my ridiculous bb/h numbers.
Right now, I'm hoping for more marginalised games such as stud, 2-7, badugi, badeucy, even OFC to be slowly introduced by more clients, as Holdem and more and more Omaha seem to have become tougher to easily beat, or at least more aggressive than ever (with 3,4,5-betting), and as a hoping to be professional one day I do my best to learn to master every other game with my fingers crossed that others will eventually start gambling on games they can't figure out.