Akshully, now that you mention it, (I disagree) SOAD may have been RR's last best work. I suggest Chris Goss...from Masters of Reality. He has worked a lot of QOTSA/Desert Sessions stuff and I think he has the perfect ear for what Sabbath SHOULD sound like now. And man, the first Masters cd...that was another GREAT production job by Rubin.
I think Brenden O'Brien was the engineer on a lot of Rubin's good stuff...mayhap it's time to get the band back together.