If you want to see the game's best ending, you must first find 101% of the items (the people at Rare must not realize percentages normally stop at 100). Below is a list of items you must collect to attain that lofty number:
201 Golden Bananas (one is the Rare banana)
40 Banana Medals
40 Blueprints
20 Banana Fairies
10 Battle Crowns
8 Giant Keys
Rare coin
Nintendo coin
It should take somewhere around 60 hours to find all of these items, perhaps less if you use this or some other guide. Once you have everything, you'll be ready for a hilarious ending that hints at a lot of future possibilities for Donkey Kong videogames...