I don't know what is best, but we're very happy w/mounting position of our Insight in the 9xxx combines. We utilize the RH post for mounting. We like things somewhat in the line-of-sight instead of having to look elsewhere for it. We've moved Insight bracketing to a few different combines now. You can view the mounting photos I put in this little album. We use Ram brackets.

http://imageevent.com/lukowphotos/insightmonitormounting