The one thing I will say is that the Williams era did brain up the scripts a lot compared to the Letts and Hinchcliffe eras. I liked those eras but they could be a little old fashioned and cliched at times. Williams seemed to think the show should be a lot smarter, and he was probably the last showrunner the series had who believed that.
But in execution it was a bit more like getting shoddy, unfinished demo versions of what could've been stronger stories. Whereas under Letts and Hinchcliffe, they tended to know visually how to really have impact and go for the jugular.
So on that grounds, the Letts and Hinchcliffe era was superior, and everything after was downhill.