[Genesis defender]

Having played (and owned) both Civ2 and Alpha Centauri, I can tell you I prefered Civ2. I could grasp the technology concepts in Civ2 much easier than the futuristic things in AC. AC's expansion pack is nice, though.

Civ3 didn't wow me much. Although it has nicer graphics, Civ3 doesn't have as many government options. Maybe the expansion pack does, but I don't have that. If you have Civ2 already, Civ3 may not be worth the money.

Haven't played or seen Civ4.

[Das Outsider]

I could grasp the technology concepts in Civ2 much easier than the futuristic things in AC

I love the idea of anthropology, but not the study of anthropology, per se--or anthropologists in general, for that matter. Civ 2 was a way to both enjoy playing a PC game and approximate historical development, in a sense.

[Harmless Teddy Bear]

Civ3 was not worth the money. It has some nice concepts but the graphics are lame. I bought one expansion pack but not the second. It was not worth it.

Civ4 looks nice and feels nice. Your workers can do so much more then just "irrigate, mine, road, repeat" and the religion concept is quite clever. You can build a missionary and convert your neighbors on the theory that if you have religion in common you have values in common and so you are much more likely to be allies.