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.
Just like zelda, the civ game most people prefer is the first one they played.
For me its civ 2. The advisors and building the palace and the music. Chefs kiss
Putting all the palace upgrades into the throne and having a modern-future throne in a cave.
civ2 is great too, I remember a friend playing it on the PS1