Destiny is WAY more hyped up than the MCC. So of course it will be getting more sales than MCC
Im a ps4 user, but i still know that almost EVERYBODY will be getting destiny regardless of MCC.
And honestly, halo is getting kind of boring and it starting to feel like the CoD franchise, obviously with a way better campaign and decent multiplayer. If i really wanted to play halo, i would wait for Halo 5.