Based on my personal experiences with lots of midsizer's I'd have to rank them like this:
1) JVC M70 (hands down best for top notch build quality, excellent tape deck, and it can slay many larger boxes. Heavy. Surprisingly battery efficient)
2) Pioneer SK-71 (sounds like the M9990, but has switchable line-in and very elegant design with cool multi-segment, multi-colored LED VU's. A gentleman's box)
3) Sanyo M9990 / M9994 (at normal volumes, I actually like my M9990 better than the M70. Has very classic look, too)
4) Sharp GF-9191 / 9292 ('cuz I had one as a teen and they look better than #1 & #2 above. And they sound pretty good, too. It's got well matched components inside)
I would expect the Aiwa TPR - 950 / 955 to slot in their somewhere around #2 or #3. I'll let you know whenever I get one.
Honorable mention: Panasonic RX-5150 is a very well-made, competent and decent sounding box with cool soft-touch tape controls...., but I do believe all of the boxes (#'s 1-4) above sound better, despite the "ambience" feature.