I'm going to say Tropical Freeze. I thought the levels were great, playing as Donkey, Diddy, Dixie, or Cranky Kong was cool, the bosses were nice and varied (though the final boss was a bit of a disappointment), and it all just looked great! Oh, and of course Dave Wise's music is as excellent as ever!
I guess DKCR would come after that. As for the original DKC trilogy, I think the first is a straight-up classic, Diddy's Kong Quest is probably the best of the three, but I have a personal fondness for Dixie Kong's Double Trouble. I've barely played DK64, the Mario vs. Donkey Kong games were better when it was just Mario against Donkey Kong and the Mini-Marios didn't take over everything, the Game Boy Donkey Kong was a great expansion of the original Donkey Kong, while the original Donkey Kong is... well, it's an important piece of Nintendo's history, not much I can say that hasn't already been said.
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