Thanks for the responses.

I'm leaning towards pot-limit omaha 8 because on the river you often have to make a tough laydown with second best hands, although often the bettor is making an elimination play when he's betting with one-way nuts and trying to eliminate a marginal (but better than his) hand the other way. Or in a multi-way pot a guy might be betting a a strong (but non-nut) hand both ways to get somebody with a stronger hand one way to fold.

I agree that a fish busts quickest in a 7-card hi-lo split game with no qualifier, because he will get constantly free-rolled, but the basic skills in that game are relatively simple compared to some other games, IMO (the fish lack the basic skills obviously).