Cash.
I started out playing only tournaments, but it didn't hit me til I played cash games. Felt there was more skill more creativity in play in cash than tournament poker ever could give, even if playing deepstacked. Tournaments just become the lottery when it's literally shove or fold when the final table comes. And playing poker for me is more than just for profit. You can technically control your wins/loses more, can win a little, win a lot, lose a little, lose a lot.
It's funny since I'm a very competitive person, used to play sports and games, but can't do that anymore, and I just don't like tournaments much. But I believe cash is pure poker with more skill, not worry about the blinds shrinking your stack and then perform hail Mary shoves eventually.
Plus I feel it's petty when people compare between the two when you can reload in cash, and tournaments you can't, even though you don't necessarily have to in cash.