Well Oppos aren't really the absolute best (especially the lower end ones), but I would say they are the best in their price range; Oppos offer amazing value. There are $1000+ dvd players out there, but you can get similar results with an Oppo dv-983H for $400 (or less). I own an Oppo dv-983h, and it's amazing. I also tested a Toshiba xd-e500 recently (it's only $120-$150) with the new xde feature, but I returned the unit due to ringing around edges (which may or may not be noticeable to users depending on the size of their screen and how educated they are to notice flaws). Actually, turning saturation up slightly on the Oppo dv-983h produced similar results to xde with the HDTVs I was testing on, and I also found, oddly enough, that enabling DNie on Samsung televisions wasn't too far removed from what XDE (I think XDE does increase sharpness slightly though, to my eye-but you get a nice ringing effect and what also appears to be edge enhancement) was producing image-wise. The deinterlacing quality on the XD-E500 is worse than on the Oppo dv-983H, the XD-E500 doesn't have aspect ratio control for non-anamorphic dvds, and the Toshiba also has inferior audio support (and output), but I'm also comparing a $150 player to a $400 player. The lack of auto resume after the Toshiba player shuts off was a tad annoying as well. If anyone cares, I only tested PQ with HDMI outputs.
Anyway, Blu-ray and HD-DVD are better than anything SD can produce, but I have a lot of SD material that just isn't available in HD (and I question if that situation will ever change).