It depends what kind of happy I'm looking for.

Townscaper - this is my go-to for just kind of chilling out. Just plonking down buildings and seeing what configurations they make is just so relaxing. There's no points, no goals, no competition, not even any citizens with needs that must be fulfilled. You just build nice cities.

Slime Rancher - the slimes are cute, and just so happy to be alive. There's something about a bright pink slime bouncing past, with a massive smile on its face as it cries "wheeeee!" that reminds me there are indeed reasons to live.

Maneater - this is a different kind of happy. A cathartic, violent, murderous happiness, as I pop inflatable unicorns, sink yachts, and launch myself at unsuspecting golfers.