I started with the original in '91. Played it beyond death.
Had an instant Civ-gasm when I saw the "statue" graphics and moved to Civ 2 as soon as it came out. I modded it pretty heavily and played Civ 2 (including it's expansions) until about 18 months after Civ 3's release...
Played the original Colonisation a fair bit, same with Alpha Centauri and the Alien Crossfire expansion.
Hopped on Civ 3 late, but played it pretty much right up until day zero for Civ 4, including PTW and C3C. Did some very basic mods for my own use.
Civ 4 day zero was extremely disappointing, persisted through a few patches, found some good mods (Didn't mod anything myself with this game... I don't know Python and the XML stuff and animations that people came out with were awesome) and then with Warlords and BTS I'm actually still playing it concurrently as I play CiV, because obviously it has a lot of TC mods as CiV's source hasn't been released yet.
I hopped on CiV early this year when I got a computer that I was comfortable could play it well. I'm certainly no more disappointed with it than I was with 4. After a few more patches, maybe an expansion or more gameplay mechanic focussed DLC, and after the Source is released to the Mod community, it'll be elevated to the status of Gaming Crack just the same way that 4 was....