If you mean non-computer games: Magic the Gathering and Go are my top picks. I'm not good at either (due to lack of time to practise) but they are my go-to game

If you mean non-computer games: Magic the Gathering and Go are my top picks. I'm not good at either (due to lack of time to practise) but they are my go-to games when I and an opponent have coincident free time. For computer games, I'd put Crusader Kings, Stellaris and Cities Skyline (the latest is so ridiculously spec hungry)