Of course Potter is better, because Zidane could never do what Potter did with Brighton.
And if he had been given time at a serious institution and not a clown show, he would have shown that in a big club as well.
On the contrary, Zidane will never succeed in any other club apart from RM and possibly a loaded France NT.
A coach that can only succeed at one club and no other club is not a top coach. Accept it