In order of preference.....
1) Hold #Em or Omaha Tournaments, Live or Online, as long as they are well-structured, by which I mean, deep-stacked slow clock stuff.
2) Omaha High Only Cash, Live or Online, though Online is more profitable for me, simply because it"s much quicker, & I can two-table.
3) Omaha Hi-Lo, it"s almost impossible to lose money if you know the basics, though, probably for that reason, the liquidity is very thin.
4) Hold "Em Cash, Live, really for the social aspect, it"s fun, & again, tough to lose. I never play Online Cash, I"d rather stick needles in my eyes.