It's impossible to say, really. Ping-Pong, Archery and Swordplay are the ones I would say, depending on which one I played the last. Basketball grows on you as well, as well as Wakeboarding, but they are nowhere as fun to play against each other.
When you've had enough of one sport, you want to move on to the next. I think that's the main strength of Wii Sports Resort. It's not just one good game, but 12.
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