what is the most skillful and least lucky game of poker?

I'll get the ball rolling.

I think fixed limit omaha hi/low

Play money any form.

I remember Daniel Negreanu said Stud has most skill invloved. I tend to believe that.

Probably a stud variant - primarily because it is limit and therefore pretty mathematical/low variance and also because it requires solid memory skills to remember opponents down cards (Especially live).

GL GL GL

my two cents: I don't know the answer as I've rarely played anything else than NLHE, but the "skill" of a game i.e: how much a strong player can outplay a beginner, is something different from luck imo. For example in tic-tac-toe there is no luck, yet that doesn't make it a skillfull game because the strategy is too simple.
Similarly, because limit forms have less variance than no-limit ones on the short term, doesn't mean they require a larger amount of skill to outplay the opponent. It should be however quicker (less hand played) for the skill to manifest itself in the limit ones.
There should be a difference made between pure skill (on the long term) and variance-adjusted skill (on a finite number of games).

First of all, games played at a table in a casino require the most skill because you're eye-to-eye with your opponents, not behind a screen. I'd tend to agree that 7 Card Stud requires the most skill and overall poker talent than any other game, but Texas Hold 'Em and other fast-moving games can also require highly skilled and composed play.

Low variance is different from high skill gap. For example, PLO has bigger variance than NLHE, but it has a bigger skill gap aswell, meaning you can keep learning and adjusting alot more, because every hand is like 6 holdem hands.
IMO the best skill game would be heads-up deep stacked no limit omaha hi/lo, or courchevel (if it has a hi/lo version), followed by holdem.

no limit games are tougher than limit for sure

Imo there's no better way to exploit blind aggression and general poor play than in Razz. Unfortunately Razz isn't very popular at low stakes or among poor players.