Chilibunny

Going to buy X now and Moon when it is released. I don't want Alpha Sapphire yet since I played Sapphire and Emerald through like 20 times, will I miss anything cool? Mega Lopunny and Gallade, but... you'd assume we get them in gen 7 games too?

Well, both games have ineresting unique features. X has gen 6 pokemon, trainer costumisation and roller skating. Oras has an upgraded pokenav specifically the dexnav and the areanav. The dexnav is pokedex completion tool which also helps catching the pokemon you want including (up to 3) perfect IV's. The areanav helps you manage berries, trainer rebattles. You also miss primal evolutions and soaring. Soaring is flying without hm in overworld map.

Also some stroy elements in oras differ from the original games including additional story content (not that great though).

Gen 7 will keep mega evolution but only for nostalgic reasons, so they won't be that prominent (might be end game).Instead you get Z moves.