First: I don't think this post fits here, I'd go like off-topic or something like steam discussions, not sure myself

It depends on whaat you want to do honestly, I'd say PEAK is rather boring if you're playing on your own, it's a game to experience with friends, meanwhile SValley can be experienced in single and is in fact quite relaxing. Stardew does have possible co-op but it's solely up to you which one do you want to experience and where are you willing to put more time even when the hype dies