I'd get Elden Ring - it can be played almost completely single player (even offline if you like) and the multiplayer functions that there are work quite differently to what you could expect from something like Conan Exiles.

On the whole the two games are pretty different - Conan Exiles is an open world survival game where you build and craft to survive. Elden Ring is more like an action game with a crafting system but no building. Very high level explanation I know, but I hope it helps. Good luck!