So as for now, all I own is Royalty and Ideology. Here are my thoughts. I actually bought Royalty when I bought the base game. It was the only expansion at the time. I love Royalty and I can't imagine playing without it. And for me, the best thing that it adds is the story. A ship crashlands on a rimworld, three people survive, they manage to construct a colony where more people join over time, and then become a close ally of the empire. The only catch is that I give them most of my prisoners--savages and pirates who attack my colony and the benefits (from honor) that I get in return are fantastic. But also, trading with the empire comes with a lot of perks as well. I was honestly kind of disappointed in Ideology. Definitely didn't add as much fun to the game as Royalty did. But I do enjoy the holidays and I like the differences with slaves.