Gameplay is the same for all of them, just the newer ones add little things from the previous ones. Overall they are all pretty much the exact same though. The only reason to play Cultures 4 from Cultures 3 for example, would be to play new maps, not to experience a ton of new features. They're that similiar.

The difference between 1 and 2, from 3 and 4 isn't much. The graphics are sharper and "improved" in the latter ones, there's a new interface, some new small things added, but gameplay is the same. It's one of those game series where they didn't ruin or change the gameplay from one game to the next, like sometimes they do in a series.

The games do require patience, as it's a city building game, with a focus on your people and keeping them happy and occupied. There can be a lot of micromanagement in the game, but once you learn how it works, it all becomes easier to play. For example, some might not learn what the posts do when they start to play, so they might get lost playing and feel pathfinding is broken, when in reality they just aren't playing the game the right way.

I'd go with 3 and 4 if you had to choose, as they are the "advanced" versions in the series, however, if you happen to love the gameplay and games, also play the 1 and 2 in the series, as they are just as good with their style of gameplay. There really is nothing "bad" about either of the games, I bought them all at once and I started with the first one first, even though the others are more advanced, and I still had a ton of fun playing it.

The games are repetitive though, as with all games like this. Why? Cause you build the same way almost every time. Maps are varied and offer dfferent challenges, sometimes you might have to fight, other times maybe not, maybe you have to buid slightly differently or chop trees down cause you're in a dense forest this time. But you're basically doing the same thing over and over again on each map, trying to fulfill the same needs, just with a different challenge or way to do it.

I think the story is okay in the games, it's nothing "deep" or really engaging, just a light hearted adventure, or at least I thought so. Great voice acting for the storly teller I thought.

If you love city building games with a focus on the people, where they even have their own names, jobs, and children, then these are good games to try. I'd say get the 3 and 4 ones first, then the other two if you really like them.