Back in the Civilization saddle...

I'm thinking of getting back into the Civ series after ~a decade away. Graphics make no difference to me. And alot of openended games in the last few years have an intended path if you want to optimize experience points, for example - and I think that's a waste. Never do more than 1 playthrough. I'm much more into going different ways with a game and a decent challenge - like say winning by the space race, most points, or domination in civ 2.

Which civ game do you guys think I should get?