I wouldn't say I don't like Phione and Manaphy, though I don't think they really seem like legendary Pokémon. I mean, they're rare, but so are Rotom and the pseudo legendaries in most regions, so I don't see why those two have to be considered legendaries.
For the one I actually dislike, I'd have to say Arceus. It just seem like it kinda stole the fame from Mewtwo, who was supposed to be the world's strongest Pokémon, but completely dominating it with the highest leveled Pokémon you can encounter in the wild, and with it's title as Pokémon God, which just made me dislike it really much. And to add to that, I really hate its design. I never expected the God of all Pokémon to be a space goat :<
For the one I actually dislike, I'd have to say Arceus. It just seem like it kinda stole the fame from Mewtwo, who was supposed to be the world's strongest Pokémon, but completely dominating it with the highest leveled Pokémon you can encounter in the wild, and with it's title as Pokémon God, which just made me dislike it really much. And to add to that, I really hate its design. I never expected the God of all Pokémon to be a space goat :<