I still play Civ 1 every now and then. I just love the aesthetic of it. It doesn't feel dated to me gameplay wise at all. I attribute much of my knowledge of history as a kid from reading the Civilopedia.

From my perspective Civ III was the best of the series however. I always loved building massive empires and Civ III was great for that.

Special mention to Civ: Call To Power where you could build underwater and space cities in the super advanced age. That was fun! I wish there was more of that.