The gulf between Burrow and Hurts is massive. Have you watched a Cincy game? The throws he is capable of regularly making are incredible. He is one of those QBs that is an instant 10 win season if healthy. Thus far, he has also done most of his work running for his life behind a terrible Cincy OL. If you put Hurts behind that line, they don't even get close to the Superbowl. He is undeniably going to be one of the top QBs in the league for the next decade plus.
There is an argument to be made that Herbert is not in that upper echelon yet since he really hasn't show to be a winner yet, but I'm not sure sure that isn't because the team around him has not been quite good enough. Like Burrow he can make all the throws, but he is certainly a peg lower I agree with you there.