freethink
Prince
It also was nice for scenarios, since it increased the number of era and culture appropriate leaderheads available. I remember that medieval Lincoln was used for some Burgundian king in the Middle Ages scenario from Conquests.
Also, since Civ 3 had only 4 eras, it was probably more manageable. I haven't played unmodded Civ 4 in years, but IIRC, it has like 6 eras.
I thought Civ 3 had the nicest tone of any of the Civ games I played (3,4,5). Civ4Col also had a nice tone, but I guess it's easier to make a tonally consistent game when you're focused on one area and era.
I didn't much care for the Civ 5 UI, either, but I did like the terrain and leader graphics. Nor did I really like Civ 4's UI, although you and embryodead both made it better by turning it grey and brown respectively. I liked how the Civ 3 UI kind of looked like parchment, that added to the historical feel.
The nice thing about Civ 3 is, even though it wasn't very moddable and had some flaws is, it tried to make all the eras distinct. Distinct music, leaders changing clothes, advisers changing clothes. The eras don't feel nearly as distinct aesthetically in Civ 4, and not at all in Civ 5, where, from 4000 BC to 2000 AD, there is the same music, the same leader costumes, the hyper-modern UI.
Completely agree about Civ 6 looking like a Facebook or mobile game. I found it very oftputting, I played at most an hour or two of Civ 6, because my brother has it and I was curious. I also think the Civ 6 leaderheads are a big step back...far fewer voiced lines, way more cartoony, and not even a full background.
Awesome
It's not the straight coastline that I dislike, but whenever you have a coastline that should be rounded or diagonal and is just blocky. I'm sure they could have easily fixed this in the exe, which, IIRC, is the only part of Civ 4 that is still not moddable, almost 2 decades later. Civ 3's coastlines seemed less blocky to me.
I like the aesthetic of Civ three so much I almost went back to this game, the biggest thing holding me back is not being able to select multiple units at once, and the religions and spies of Civ IV are more fun and Leoreth's Rhyes and Fall is the default way of playing civ now. But Civ three had the tone like others have said as truly being timeless and yet ancient in a charming way. It was worth playing just to see the leaders change, also Civ III leaders had more personality they would not threaten but sometimes declare war if demands were not met, they would also take advantage of right of passage agreements and betray the leader (The Human Hive in Aplha Centauri did this too)