Toshibas new DVD/VCR player won the most recent secrets shootout. Which means it has, after rigorous testing, the best picture quality of any player they have reviewed. Quite interesting results.
http://www.hometheaterhifi.com/cgi-bin/shootout.cgi?function=search&articles=121

However, it is unlikely that anyone of us would notice a difference, these people test with magnifying glasses and crazy test patterns. And most people just want their DVDs to look good on their screen.