I actually have trouble picking between them.
Both succeed brilliantly at what they set out to do, MP3 in proving that the Wiimote can be a superb and immersive first person control method, and DKCR for merging the roller coaster spectacle of a AAA blockbuster with the elegance and challenge of a traditional platformer. Both look great and play even better.

They're vying hard for the #8 spot on my top games of the 7th gen.

I would say a tie between Donkey Kong Country Returns and Metroid Prime 3: Corruption.

Can't choose between the two because I haven't played Donkey Kong Country Returns 3D yet.

I'd say Metroid Prime 3, but DKCR was also a very fun game!

DKCR was awesome, but I prefer Prime 3 (The best in the series IMO).

I'm a massive DKC fan so DKCR (DKC is my favorite 2D platformer franchise and by far the franchise with the best music)

I was actually happy when they showed DKCTF at E3 instead of a new Metroid game. I know metroid is brilliant and might have helped the Wii U more, but I just love DKC. I also thought Crancky Kong was awesome.

Both excelent games, DKCR was the best.

Dk was my favorite game on Wii. Metroid Prime I only played for a few minutes (I can't stand shooters)

I didn't like either. Not a fan of FPS games, and I got bored of MP3 very quickly. DKC feels like a bastardization.

DKCR imo. Both are great though.