Different beasts. Godfather is epic, trans-generational, big director, a massive statement about American cinema as art which is maybe what's getting up Jon's nose. Harder They Come - "third world" cinema, one of the few films shot in Jamaica (well, telling a Jamaican story, I'm sure it's background glamour in loads of Hollywood chuff), much rougher round the edges but more genuine, is centred on music, and quite meta- in it's reference to cinematic violence (in a way that The Godfather indulges and fetishizes).
I find it hard to say. It would be HTC but the storytelling in The Godfather is just so good. Evenly matched.