My Panasonic DMP-BD50 Blu-ray player outshines my Denon 2910 Universal DVD player when it comes to playing standard DVDs, particularly in terms of automatically figuring out the correct aspect ratio, so I don't have to go into setup to manually switch between film-formatted widescreen disks and 4:3 formatted old TV shows. It also shows the (admittedly-rare) subtitles in English-language films like Attack of The Clones, when Chancellor Palpatine's holographic desktop intercom pops up, which the Denon didn't show. The Denon is now reserved for SACD and DVD-Audio playback.
I second Mark's observations about the image quality of Attack of the Clones, the mid-air chase scene early in the film being a wonderfully-immersive experience when shown with a projector. (I use a Panasonic PT-AE2000U 1080p24/i60 LCD projector to throw an image 9½' x 5 1/3' high.)
My theory is that the less video compression that's used to make a SD DVD, the better it looks when upscaled. I also find that close-ups of faces, and other large images on screen, tend to upscale more successfully than crowd scenes, since there's less detail crammed into the frame and thus less need to discard details in making it fit on a DVD. Even some Blu-rays lose detail in long shots. The Chick Corea DVD box set Rendezvous in New York, with 9 disks each containing a single set by a different acoustic group in Chick's career, each of them less than an hour long, also looks and sounds nice - in part, I'm sure, because very little compression was needed to fit them on individual DVDs.
I've got a pre-HDMI Yamaha 5.1 receiver driving Paradigm speakers, so I snapped up a BD50 before it went unavailable, since it was the first (and only) player at the time that decoded all the lossless formats internally and output them in 5.1 via analog RCA jacks (or 7.1 via HDMI as bitstream or PCM). A newer model that had 7.1 analog outputs had been announced, but since the BD50 had been in scarce supply for half a year after its announcement and had only really become available right as its successor was announced, I didn't want to risk having to wait another half a year.
Of course, there turned out to be no wait at all for the next model, but just the same, I've never regretted getting the BD50. It has excellent sound and video quality and has never balked at any disk I've fed it, even though I waited nearly a year to do my first firmware upgrade.
I can't testify as to either of my players' comparative merits vis-a-vis the Oppos, since I've never seen an Oppo except on the web, but I'll say this: the sound quality of a concert Blu-ray's lossless audio track played by the Panasonic DMP-BD50 is as good as the sound quality of an SACD or DVD-Audio disk played by the Denon 2910.
I've got a shelf-full of SACDs and DVD-Audio disks, but I don't expect to see much more being released in those formats, given the acoustic parity of Blu-ray's lossless audio codecs - and Blu-ray's much greater market penetration, aided by the merchandising value of visuals.