[Iceman]

Omaha-8 is easy to learn, and is very profitable against bad players. That said, it's rarely played live above the 5-10 limit, and while it does exist online at 3-6 and higher those games are rarely profitable even for an expert player. If you plan on staying at low-limits it's a good choice, but if you want to move up eventually you should probably choose something else.

Stud is a difficult game to learn to play well, but an expert stud player can have a significant edge in almost any game - loose, tight, passive, aggressive. While there are a lot fewer strong stud players than strong holdem players, there aren't as many total fish at the stud tables since most new poker players are flocking to holdem games.

In B&M play, limit Omaha-8 and limit high-only stud are the most popular versions of those games by far. Online, there's also a lot of pot-limit Omaha high, pot-limit Omaha-8, and limit stud-8. Pot-limit Omaha high is the most popular game in much of Europe.