Crusader Kings III: Royal Court Review (RubyClaw)
I think this DLC is underappreciated for some reason. My main issue with it is that most of its content is locked behind being a King/Emperor, and I think a "smaller court" for Dukes/Petty Kings would have made a lot of sense. But the court itself adds a lot of flavor and character to the game. I love the court events (Paradox, please add more events in the future, they are getting repetitive after so many years), all the court positions, and of course the Artifacts which were a wonderful addition. Another important feature that not enough people talk about are cultures who were greatly improved, the option to diverge and hybridize them, and generally all the content related to them. At the end of the day, among the "expensive DLCs" Royal Courts is probably the least crucial one and T&T and RtP are better, still it is a solid addition to the game that I would recommend.