You're right, that is an *extreamly* hard choice. I'll have to go with Octillery, though, you can't beat a kawaii fire-breathing octopus with a cannon for a mouth. It reminds me of the Octoroks from Zelda.
I vote for Politoed. Octillery is just strange. Look at its movepool. Lock-on, Bullet Seed, Solarbeam, Sunnyday, Psychic, Auroa beam, Psybeam, Flamethrower, Rock Blast. You can safely say Octillery is no normal Pokemon.
And it is too slow.