Yep I defineately think I, II, III, and IV all should have been included. I never played I, but I did play II. It was what introduced me to the idea of strategy games. In my mind civ II is the truest of what the civilization games are all about. III improved it a little bit in all areas, and had the one huge change of introducing culture and civilization borders. Culture is in my opinion, the single biggest step in the civilization franchise. IV, in my opinion made the game much more mainstream. It was made much less tedious, but by doing this it lost it's great epic feeling.
So I'd say IV is the funnest at first, but gets boring the quickest. III and II are the true civ games.