You know, actually... I think I'd like someone who knows comics but ISN'T a writer. I think a writer, no matter how good he can be as an editor, would succumb to the natural tendency to actually have the full-line following his ideas.
Let's take a simple example : Red Hood.
If, say, grant Morrison was to become editor, would he support the current series (Red Hood and the Outlaws - 2011 and 2016 runs together) or would he feel that it has taken the character too far from its roots (to say the least of Bizarro and Artemis which are very unique to RHatO) and needs to be canned ? And if it's the latter, will he want to have Red Hood return to the deranged killer he had become under his pen ?