Maybe it's because it was the first one I played, but something about the 2d aspect of this game gripped me. I don't have the same love for the games that came after it, the 3d graphics somehow take me out of the historical element.
The fact that in the older games you are basically playing on a map, gives off this almost board-game feeling that is cosy and immersive. (I know that civ was inspired by a board game)
Playing civ3 as a kid really made me feel like I was in whatever era I was playing at. Still remember those jazz fusion tracks especially.
None, I didnt play it enough to form good memories.
CivII however, my favourite is playing against my dad and big brother on LAN. I was too young to grasp such a high concept game and should have been crushed. Id built a temple and a marketplace in my one city, and my brother turned up with a whole battalion of cannons and knights. I had the single warrior that you start with. My lone warrior took out his entire assault of like 15 advanced units. He was piiiiiiissed.
I dont know if I was just super lucky, or if my dad had set it up to give me a massive handicap or what, but its been about 30 years and im still chuckling typing this out.