Which Wii game to choose! HELP!?

I now got enough money to get either Donkey Kong Country Returns or New Super Mario Bros Wii. God knows why the price for new SMB is still in the 40's - 50's price range, though. I love both DK and Mario games. Any idea which I should pick? I got enough wii motes for four players for SMB wii and you should know that four is more then enough for co-op in DK.