First off congratulations on the bub it's a awesome feeling second I personally would go with xbox I personally have a lot of faith in xbox the controller just feels nicer and I am so excited for the next halo as for backwards play they just said at e3 they are releasing old games on xbox one all you do is put your old game save it to hard drive when that game has been converted as for destiny I'm not sure if they are still letting you transfer but good luck son