Larry DiTellio would be one choice, an SF-inclined veteran of NYPD Blue or similar would be another.
But there has to be a script editor/line producer who's in a position to say "Joe, this is rubbish, rewrite it. or we don't make it."
NOooooo!!! NOT Larry DiTillio! Remember him? Architect of such gems as 'TKO', 'Eyes' and 'GROPOS'? At least you need somebody someplace close to JMS' level and it ain't DiTillio.
Hate to disagree with you, but I have to defend DiTillio here. Not only did he give us "Born to the Purple" but he also gave us the incredible "DeathWalker." Sure, he's no JMS. But then, neither is JMS ... "eeeeee-kaaaa-raaaaa" anyone?
You take the good, you take the bad, you take them both and there you have, Babylon 5.