For newcomers to the world of poker, NL Hold'em is probably the best form of poker to get started with. It is, by far, the most popular form of the game spread today, and it is relatively easy to learn the rules.
Pot Limit Omaha is the second most common poker variant, but mastering the rules and how to read the board is a bit more challenging than in Hold'em. If you and your friends find NLHE getting a bit stale, then you may wish to make your next poker game with friends a PLO event. PL Omaha tends to have bigger pots and more action than NL Texas Hold'em, so it's perfect for jaded Hold'em veterans.
For more info about this game, check out this PLO strategy guide for beginners.