I personally prefer Dialga. It's design is a lot better compared to Palkia's, in my opinion. Though, I think it would have made a lot more sense if it were either dragon/water or dragon/ice instead dragon and steel. Its body color is primarily blue, so, yeah… plus, they have a tradition of relating Pokémon's color scheme with their typing. As for Palkia, I think it could have been dragon and psychic. d: