RTS.
I never played C&C, I played one round of StarCraft when it first came out and only got 1 and 2 this year, played WarCraft2 mostly with cheats, barely managed to get through WarCraft3, but cheated again at the end of Frozen Throne, only really played Galactic Battlegrounds because it's Star Wars and for the same reason played Empire at War - on easy.
I'm too slow and deliberate, my main MO is turtling -> researching -> steamrolling; which most games don't actually allow to be a viable strategy.
Especially the oh so fabled StarCraft, apparently. Against random people (or even the AI...) you lose against early rushes, and even when playing with a friend who agrees not to lolrush, the one who gets to the expansions first wins (which is also true in EaW MP). That's a stupid system and I don't get why people like it.
Sins of a Solar Empire was the only one where I could do what I do and once I conquered a 250+planet galaxy three times it got kinda boring. And it counts, it's not really 4X, it's real-time 3-and-a-half-X.
And looking at the various Civilizations, I'm probably too dumb for turn-based strategy.