I never tried the Sony 75H, but did try the 85H multi-disc version, and have used the 77H, 700H and Pioneer 400V & 410V. If you're lookin to upgrade, the one I'd currently recommend from among these is probably the Pioneer 410V.
It's been awhile since I used the 85H, but if memory serves, there were two things about it's PQ that I didn't particularly like. It did not pass full vertical detail (e.g. on DVE's multiburst test) in the HD modes, and there was some horizontal edginess to the picture that bothered my eyes. Consequently I passed on that model.
The 700H appears to be basically a clone of the 77H (the player I've used for the last 6 months), with just some minor cosmetic changes to some of the menus, and buttons on the front panel. It looks and sounds the same as the 77H though in all my tests. Both are excellent players, and do a great job on most DVDs.
All 4 of the most recent Sony/Pio players have very similar basic PQ. But the Pioneer 410V does a better job of reducing combing on some poorly edited 90's TV shows, and has these other features that the Sonys lack:
- Gamma control
- Better Sharpness adjustment (the Sonys' sharp settings produce more obvious ringing, and the Pio also provides a softening option)
- Better virtual surround sound via the stereo RCA audio outputs
- 480i via HDMI
- USB input
- DivX support
- More playback controls on front panel
The 410V also made the following improvements over 400V units I tested:
- Better deinterlacing
- Somewhat quieter "hum" during playback (this may be somewhat subjective on my part)
- Better DVI compatibility
- Better gamma control
- More reliable 4:3 settings for HD modes
To be fair, the Sony 77H & 700H also have a few features that the Pioneers don't, including:
- Better pause mode (paused video frames look more jagged on the 400V/410V)
- Optical audio output
- A/V delay setting
- Bravia Sync
- Slightly more quiet/pleasant "hum" during playback (again somewhat subjective)
And one thing I can't really comment on is long-term reliability/durability of the Pio compared to the Sony, since I've only used the 410V for a few weeks.