It depends on what you're into, but I love turn-based tactics/strategy games, so the XCOM series (and the numerous games influenced by it) are top notch for me. I like the gameplay loop of completing turn after turn, with the ability to easily get up and do something else if I get distracted at any time.
For more of an action game, my favorites are the Souls series, Bloodborne, Sekiro, Elden Ring, etc. The challenge is unmatched, and there are no waypoints or quest logs to make you feel like you're mentally juggling a dozen tasks at once (which I find exhausting and off-putting). I like being able to just pick up the controller and simply know that I need to make progress in that direction.
I do also enjoy competitive multiplayer games, but I haven't liked the direction that those have gone in recent years: with battle passes, dailies, and grindfests, I'd rather avoid getting trapped in that FOMO cycle, so I don't have one that I play at the moment. (Unless you count online chess, lol)