Tennis is okay, Out of the WiiSports collection I'd have to go with Bowling...
and I was slightly disappointed with Baseball, sure batting is fun... but the fact it doesn't follow baseball rules got to me.
I definitely spend more time playing Trauma Center, and Rayman more.
My fave is Tennis in Wii Sports. Even though U can't control where you move, I think it's pretty sleek how you can do slices and different shots depending on how you move your remote
Bowling is annoying the crap out of me now (due o my inability to bowl over 200 with any regularity), and baseball is frustrating. Boxing.......... don't even get me started.