Both games of those are shit.
I choose Vanquish.
:S, Vanquish isn't a party game. It also demands more concentration and attention therefore playing while your also chatting with friends would be very hard, and end of the end you would be good at neither.
I think the premise of realistically playing sports with your body is idiotic.
Why not just go outside with a ball? Get two rackets and play ping-pong on the kitchen table?
I seriously don't get it...
I haven't played Wii Sports or the Sony Sports Chamions but back in the day and even rescently I spent an hour every day playing Wii Sports, it is still awesome.
I only played Golf and then after a 6 hole game, some tennis for a quick final showdown. I never got into bowling and boxing that much.
I don't think you've played Golf in real life it can be very frustrating, their are mosquito's on the field, the ball can get lost and their's a ton of walking which wouldn't hurt so much if their weren't so much mosquito's.
But Wii Sports golf is legendary, you can play with friends while maintaining a fluid conversation and only stop when someone really needs to concentrate, so it functions as a great background activity and can open people up. You have a stiff guest at your place, who isn't talking much, put Wii Sports Golf on and s/he will open up more.
Playing Wii Sports was the only good memory of that cursed console.