I've played both games and like them equally. Kenshi has a lot more stuff to build, it's quite complex, it has NPCs to add to your warband and a tactical feel to it when trying to build reputation but not get wiped out by a faction you have angered.

Valheim is more casual, you're on your own (without mods for NPCs), building is nice and I enjoy exploring the randomly generated worlds. I think Kenshi would provide more to do, long-term, but I like both games.