The Martian Ridley to this is different because he was given a completed film, the Martian is the book, he had no narrative input. He just put his beautiful visuals into it. That's all.
Ridley is only as good as the script he's given or chooses and he can't choose a good script.
Those saying the alien was the worst part of covenant, sure, but that's only because the story teller chose it that way.
No matter how much everyone loves him, he's not right for the franchise, Prometheus and covenant, could have been a new universe, if he doesn't like alien, don't make an alien film. He has enough money he can make his own new universe movie, it all boils down to greed and yes men