There is no competition with Emerald. FR and LG were interesting, but Kanto overall is kind of boring now. The games have evolved so much further. For obvious reasons (better storyline, Battle Frontier), Emerald is pretty much strictly better than Ruby and Sapphire.
Firered/Sapphire used to be my favourite, but not they're not as good as Emerald, because Emerald is a lot harder and I still have a lot of things to unlock. Also Sapphire has two p's.