I favor synthetic. On my old 5.0 Fox body I pulled the valve covers at 266,000 miles. Everything was clean as could be in there. That car was driven hard and sat in a LOT of heavy traffic. But.. today's oils are all good. If you change as often as suggested, pretty much any current oils can get you past 200,000 miles without issue.
By the way, I use Mobil 1. Just because it is easy to find anywhere and priced fair.