Hmm,
TWW has a commanding lead, eh? I wish I remembered more of that game and its boomerang, but my
TWW disc is borked.

Anyway, out of the games I've played multiple times and have a pretty good memory for, Twilight Princess' would be the best to me. You've got precision IR aiming, it locks onto stuff, what's not to like?
The opening post mentioned usefulness. The boomerang is your friend in
LoZ. I can't remember if it'll stun a Wizzrobe (and if I'm remembering right it won't stun a darknut), but it definitely stuns a lot of stuff and even kills Keese and such. It moves in 8 directions too, which is really good for the four-direction-walking Link. I guess I think it's the most useful, but even so I voted
TP.