All the games except Takamaru's have significant merit, but Octopus Dance is light-years beyond the rest in my book. It's Space Channel 5 with independent arm control, motion-leaning, and inter-move transitions. I did not expect such glory from Nintendo Land. The music rules, too. The buildup into Stage 5 and the Extra Stage is the highest a game's made me in awhile. Bravo. I got the 5 stamps and platinum trophy very quickly so it'd be cool if it were longer/harder/more varied between runs but you could say that about any of these minigames that you love. I'm happy with what I got.
I give second place to Falcon's Twister Race. It's a magic moment when you hit Area 9 and the music kicks in.