[Dr Kain]

Honestly, Jan is no more or less annoying than the likes of Ban, Ryouga, Kai, and Alata. He's from the jungle, so he is supposed to be hyper.

As for the mecha, while I'll agree they aren't the best, GekiTouja is awesome because he is not some heavy mecha. He is skinny and can actually move around.

My favorite ranger though is GekiChopper. I do not know why, but I really liked his personality.

And Matrix is pretty much dead on why I like Rio and Mele. They were more than just there to cause evil deeds, they had development, they grew, etc. That is the same reason why the Saima Clan are my favorite villains in all of Sentai. Even though they started out as just beings wanting to take over the world, there was more to them because they were siblings.