Hm, from what I've seen, I'd have to say Civilization, and all games like it. I watched Game Grumps play it, and I've seen friends play it occasionally in real life, but, and let me emphasize first that I perfectly understand that everyone has every right to like what they like, and this is not a case of the game being bad, but me simply being unable to pick up on what characteristics people love about it, but it is one of the few games where I cannot even comprehend how people enjoy it. It's just that foreign to me. I don't really like FPS or racing games for instance, but I feel like I can at least grasp vaguely how people can enjoy them, but Civ, I can't even comprehend what aspect of it people enjoy.
Just to reiterate, I completely understand that it is probably a great series, and that I am the one missing the point, and that me not liking the game in no way makes other's crazy/inferior for liking it.