I think most people would say holdem, and overall it's the best game. I kind of prefer to play the other games, mainly because I grew up with a lot of them. But also because there are more resources for players to learn on holdem. Everyone plays it. The level of play on an average holdem player right now is significantly better than it was 20 years ago.
Omaha, Stud, 2-7 variants, Badugi, those are still skill games, albeit with a higher level of variance. But they are typically probably softer than a holdem tournament. Especially if you are playing mixed games like 8 game, HORSE, 10 game, etc. In those cases players will often be best at one or two game types, and not nearly as good as others. Which makes the games softer. Not to mention they will generally have less players, which makes the likelihood of reaching a final table higher, and that is where the money is.
