Well, that was a hard choice, but after some hesitations, i have picked the third movie. There is a several reasons:
1) Hyp's gang. I dislike them;
2) The broken link in the plot(Why it was impossible to grown ups to just go to the Mysterious Beyond and look for the solution by themself?;
3) The whole movie was blush. Even the way it was drawn.
That is my opinion.