After a series of test in several stand alone players with diferent media the results tell that DVD-R has more compatibility with more players, for detailed info take a look in here:
http://www.cdrinfo.com/Sections/Articles/Specific.asp?ArticleHeadline=DVD Media Format Compatibility Tests&Series=0
http://www.cdrinfo.com/Sections/Articles/Specific.asp?ArticleHeadline=DVD Media Format Compatibility Tests&Series=0