1UPT kills the game, and the devs won't get off of it. The problems within Civ 4 are fixable by better means, but the mentality of the series moved towards making it a skinner box rather than a game.
I still think Civilization 2 is the more interesting game for its time, but Civ 4 mods give it nearly unlimited replay value and extendability.
If I were to make a new Civ game though, I wouldn't look to the earlier games and try to copy them. I'd do things very differently, probably get away from tile / unit management altogether and streamline the military aspect of the game. The civilization-building decisions have always been more interesting for me. I would like a civ game where the military aspects are largely automated - you declare war, manage your civilization's overall military status / status of internal revolts, and the generals do the fighting. But then, I see this as a way ot mitigating one of the series' nagging points to me - that civilizations tend to suffer from internal instability, and this is not at all reflected in the series. I get why this isn't going to be realistic - you have to control one civilization from 4000 BC to 2000 AD, and no civilization could last that long. The military aspect automation though could be done while retaining Civ's overall take on history. I really would like the social side of civilization-building to be emphasized more, because that's one of the most interesting parts of history for me - how empires and societies face struggles both from outside and within, and how leaders manage the really big crises.
By limiting the military side of the game, it allows more game time for the things that are interesting, and it also allows a more interesting take on managing armies, military industry, and so on. The way it is done in civ with per unit hammer costs emphasizes the wrong basis for militaries imo. Militaries are recruited from the population, especially in eras where the basis for the military were citizen-soldiers or peasant levies. It would also allow the player to focus on the development of technology and science at the period where it was actually historically relevant, while early game conflicts would largely not require beaker investment since they're largely driven by population and resource availability. By industrial era the deployment of artillery and modern ships would require a whole industry and supply chain, development of oil, etc., which was in our history a really big reason why modernity turned out the way it did. Late game military in civ tends to be disinteresting, especially in Civ 4 due to SoD. I remember having lots of fun with late game war in Civ 2 because the battle options were right for the game - more varied from Civ 1 which only had fighters, bombers, and basic tanks, and the introduction of partisans when fighting democratic or communist civilizations was cool. These things could be abstracted into something that is more interesting - something that is a factor, but that happens behind the hood and is a consideration for your civilization.
Anyway Civ 4 remains my goto Civilization game due to the mod library. Realism Invictus does a good job of teaching the AI new mechanics, although the player will be able to boost ahead in techs unless playing at Emperor difficulty or higher, which makes the game really difficult to play early. Some of the tactical decisions in RI are questionable, like how early game skirmishers are really strong in the field, but they did a good job of mitigating the usefulness of SoD, and if you were playing against quality opponents, you wouldn't use a single SoD in Civ 4, but you'd deploy armies with the goal of taking cities and harassing enemy territory. Because the AI uses SoD and often has a huge production advantage, you're kind of forced to SoD in Civ 4 vs. AI.
