I, for one, really like three games in particular.

First, Pathfinder. Certainly it has its quirks, but at the same time there is a lot of support for it. As far as a class-based d20 game goes, its pretty uncomplicated. One thing it could do better, I suppose, isn't the game so much as the community. I feel the community is a tad bit elitist.

I also like Shadowrun. The setting is extremely interesting, and is at a scale that rivals almost any other tabletop setting in terms of layers upon layers of lore. The system itslef is confusing and head-ache inducing, however. I'm working on hacking (ha, cyberpunk pun) a rules-lite system to alleviate this for newer players.

Finally, I really like Betrayal in the House on the Hill. First of all, it's wonderfully pulpy in its horror. Second, the tile exploration mechanics are unique, and one I've been meaning to adapt as a one-shot for either Pathfinder or my own hombrew system mentioned above. I do feel that it can be intimidating to new players, however.