The bosses in this game just didn't seem that hard to me. It seems zelda games are just getting easier and easier. I thought that the pig guy who kidnapped the kids was a tougher opponent.
The dragon was one of the hardest bosses for me my first playthrough and that is why i voted for it. The first time i face him i didnt know u could z-target the peahets, so i was trying to get around him by constantly aiming with the wiimote. It was nearly impossible to do it that way.
I voted for Blizetta because of the slippery ice surface and when the circle of ice "spikes" drop all round you and there's no way to escape, but probably the most BORING boss battle ever is Argorok because of the unending clawshotting from one plant to the next so that you can clawshot onto his back