Having played Civilization 2-5, as well as the games made by the original team of Civilization : Call to Power 1&2,
I would say ANY Civilization game so far is a buyer and a keeper, if you are into turn based strategy games.
The only reason Civilization 1 is missing from my collection is the rareness of finding someone having and willing to sell his/her copy, I woud jump at the change;)
every Civ Game adds a little and removes a little, the one that you like most is personal flavour.
To me this one certainly ranks higher than the later Civ 4 and 5.
This game was and is the height of "classic" Civilization games.
For you people ariving at this from Civ 2 : you only will miss the old advisors (civ 5 and they still not have returned them sadly enough)
For you people ariving at this from Civ 4 and 5 : no religion, but instead you will love the stacks of doom, army units, and other things that were removed in later game.
This game is also somewhat older and a lot lighter on system requirements than later civ games, making it great to play on any device you want to. Also for a mere 4.99 (and it's often on sale for 2.49, and more rare for 1.25) you have an asolute bargain!