I would love Civilization 5, as a game, except it is buggy as hell, and the AI sucks bad. I switched to Shogun 2 as my alternative, and for now, I am playing it as a turn based strategy game. I am very happy with Shogun 2: I encounter few bugs of consequence, and the AI is decent, at least for the strategic game.

I have not yet purchased any add-ons for Shogun 2, as I am still learning the base game. I am sure I will buy RoS and maybe some others later.

Smeelbo-san