The Oppo 983H seems to be the best upconverting on the market, so I bought one for the people giving me housing at the moment. It has not disappointed here as far as DVDs go, and it seems to work well for other people also.
However, I have noticed a few annoyances about it. The player claims to play a bunch of media formats, so I connected a USB drive to play 1080p files. I kept getting messages about divx and wmv files having a resolution that was too high. Mp4 files did not play at all, such as files downloaded from Youtube. Then I found this message. 720×480 is the maximum file resolution. When I played 480p files, they look far better on the computer than they do on this player.
Another potentially interesting feature of the player is the "capture" button on the remote. It allows a screen capture of the current thing being shown on the screen to be used as the background when the player starts up. While the player can show pictures larger than 720×480, larger pictures get recompressed and quite ugly. I take it the player does not have much memory.
At least DVDs look good, and at least it comes with this nice bag: