How long have you been playing Pokemon? If you've been playing for more than 2 generations, you should know that there is no "better" version of the game. It's all subjective, and has only a few different pokemon in each version. Do some research on Serebii or other sites, and see which exclusives you like, and choose that way.
I'm getting Alpha Sapphire because I like Kyogre, and Team Aqua more, also think some of the exclusives are cooler. Both of them will be basically the same game, so dont worry.
Dont think there will be any Delta Emerald because when Gamefreak remakes a Pokemon Game, it only comes in pairs, and they never include the third game of the series.