my little appy (got to have QH in him, as he looks a lot like one) has got the BUMPIEST trot ever, his lope isn't bad, though.
I started riding some horses for a gal last week, and the gelding is bumpy, too. His lope isn't bad and man he can run... the younger mare is a lot smoother than he is. Have yet to get on the third one.
In comparison my wife's TB has got the world's smoothest trot. I can't NOT post his trot because it's just too dang natural.
It all depends on the horse and how they're built.