Phil is already playing a Mario game. Is 1 Mario game not enough?
I voted Metroid Prime 2 as well. Absolutely amazing game. I'm playing it again right now on my old GameCube, in fact (got 5 more Sky Temple keys to find before the final boss).
Agon Wastes, Torvus Bog and Sanctuary Fortress were a blast. I love the soundtrack for the subterranean Torvus Bog, just a perfect underwater track, so alien and chill!
Unfortunately, it was a dark, challenging and complex game that the mainstream crowd is unfamiliar with.