Depends on what you want. When it comes to CKII, there's what can be considered the three big overhaul mods, each offering something different for the game: CKII+ adds many new features and improvements to the game, but some people don't like it because it adds too much Prince and Thane adds in many new ways to roleplay and immerse yourself in the medieval world, but for some it adds in way too much (not to mention it's a bit unbalanced at the moment) Project Balance tries to stick close to vanilla as possible and improve on the game without changing it, but for some it's too close to vanilla Besides these big three, there's other major mods out there - each, again, offering something different for everyone. Friends and Foes is sort of like the roleplay equivalent of CKII+ - it integrates a number of CKII+'s features, but focuses mainly on improving roleplay. From what I know it's more focused on roleplay compared to Prince and Thane, but Prince and Thane has a more historical immersion focus. Magnate Lords is focused mainly on improving the economy and making it more historically plausible - the premier economy mod. SWMH is mainly a map mod that tries to make a better map set-up for the game (though that's pretty much it - there's also a SWMH-compatible version of Project Balance, by te way) Project Synergy is CKII+ and SWMH, basically VIET - it's my mod . VIET focuses on flavor, immersion, and roleplay, similar to Friends and Foes and Prince and Thane, but it takes a more minimalist approach like Project Balance, meaning it tries to keep things as close to vanilla wherever possible. It's also modular, meaning you can pick and choose (to some extent) what you want and don't want to play with, and it's fully compatible with Project Balance, and has some CKII+ compatible modules. Lux Invicta - Crazy Alt History A Game of Thrones - self explanatory Elder Kings - Elder Scrolls, self explanatory Tl;dr: Personally I prefer Project Balance, because I'm very much content with vanilla and I don't like adding new features I won't enjoy. Your pick ultimately, though. There are quite a number of options.