You'll get more out of ORAS on the whole; gives you more legendaries, more total Pokemon, more megastones, and has far superior QOL improvements. However XY will offer you the chance to have two starters - Gen VI starters and Gen I. So if that's important to you, go XY. You can get Charmander/Bulbasaur/Squirtle on ORAS by trading, but it won't be as a starter.
XI Wiki




