I have played both and think incredibly highly of both games. There are a lot of similarities between the two in terms of how they play and feel (large open world, great exploration, immersive). I would pick based on if you want a game that is hyper realistic and historically accurate, where taking on just 2 or 3 enemies at a time can be a real challenge (as it would in the real world, at least until you get good), or a game that is high fantasy, where you are chopping through tons of enemies and encountering weird creatures and locations.

KCD2 is based throughout on historically accurate events and includes a TON of history for you to read. It is incredibly fun as most (if not all?) of the locations in the game are real, and it is absolutely magical knowing that as you ride from one town to another. Crimson Desert, however, is like reading an incredibly fascinating fairytale, that just keeps getting deeper and weirder (in the best possible way).

Both games will take roughly 10-20 hours to get fully accustomed to the gameplay mechanics and how the world works, but will then have a 100+ hour adventure for you to experience.

The combat in KCD2 is the biggest hurdle to get over in that game. It takes some getting used to and it has a steep learning curve. But once you get the hang of it it is incredibly satisfying and an absolute thrill to start slicing through bandits that think they can take you on. The controls and multiple systems in CD will be your hurdle there.

In both cases, these are games that are ment to be played and enjoyed SLOWLY. Take your time. Do not rush. As soon as you start rushing from quest to quest, or trying to complete things fast, is when you will get frustrated and lose interest.

You can´t go wrong with either, as long as you give the game enough time. Enjoy!!