Pokémon Omega Ruby and Pokémon Alpha Sapphire announced

In my opinion its better to get the cartridges, since downloading them would take a day and a half, especially since you'll be sharing that connection with millions of other people.

Buy one cartridge download the other while you sleep later? That way you will always have one with you, but you can trade with yourself if you borrow a friends 3ds? That's if you want both of course.