Odolwa is the best choice of boss in Majora's Mask. He's chaotic, fun, and his chants are awesome! I actually found him harder than most of the other bosses in the game. I have never tried to beat Majora without Fierce Diety, so he's just a push-over.
Goht is my favorite because its not a repetitive battle, you have to change up your techniques to beat him, you can't always stay up on that area above water because eventually he'll start ramming it forcing you to go into the water.
I have to say, I'm irritated at the redesign for Gyorg. One thing that gets levied against Zelda bosses a lot is their predictability. Gyorg was cool because how to hurt him wasn't really readily apparent at the time, and… let's just say that experimentation (getting in the water with him) was risky. Now what have they gone and added? Yup. Giant glowing eyeball. In a place that makes no sense whatsoever. (and he looks absolutely idiotic when you do stun him)