Alpha Centauri or PlanetFall?

I've played a bit of Civ 4 (without planetfall) and a bit of SMAC. I gave up on the latter a while ago because I found it buggy. The game would freeze after a few turns of gameplay, and playing it with a fitting resolution causes it to crash whenever I try to move the camera.

Anyway, which one should I commit to? I only played SMAC for about an hour or so, so it's still new to me. I'd just need a lot of support to make the game more playable. Also, is there anything big missing from SMAC in PlanetFall?

I don't know about Planetfall, but I probably can help you with your SMAC problems. What's the version number of your copy? (To see the version number, start a game and press Ctrl-F4.) Many crashes and other problems have been fixed by patches. Also, if you haven't already done so, add the following to the [Alpha Centauri] section of your Alpha Centauri.ini file:

DirectDraw=0

If this doesn't help, please post your system specs, including whether or not you're playing on a laptop and your native desktop resolution. Thanks!

Planetfall is not really a SMAC implemented on top of Civ4, it's a Civ4 mod that shares a theme with and has some mechanics inspired by SMAC (and others that are original or inspired by other sources). I don't think it would really make sense to list the things that it's "missing" because it never tried to fully cover SMAC's features in the first place. If you ask me, I think Planetfall is pretty good and definitely worth giving a try on its own.