This is my primary question!
5DIII in RAW (esp with ML dual ISO to boost dynamic range by many stops) is something magical, to be sure.
However, the 5DIII JPEGS are also magnificent in their own way -- I keep one lying around just for the JPEGS. Somehow this camera has a miraculous ability to hold onto highlights, even in JPEG mode.
Nikon D200 CCD in RAW. It uses a Sony CCD so it's better in some ways (highlight retention and rolloff) versus the Kodak ones, but worse in others (less interesting colors). Still magical, though. I keep one lying around:
One that is often overlooked is the Ricoh GXR M-mount module. While it may share the same sensor as the X100 and Nikon D90, but it is geared a little differently.... more muted colors (except for reds), and somehow crazy good for B&W photography. Seriously, using any RAW converter (LR, rawtherapee, darktable, filmulator, all of which I've used), you convert any RAW GXR images to B&W and it's... incredible!
Lastly, of course... the Leica M9, my primary camera for these last few years and to this day. Lately, I find that Darktable's recently introduced "Sigmoid" process is very tender with the M9's harsh highlight clipping issues, the sensor's greatest downfall.
P.S.
I think Andrew mentioned this, but the 5DII is SUPER magical, more so than the 5DIII, and right up there with the M9! I have a 5DII laying around too, but don't have any photos available. Once again, using ML's dualiso module to boost the dynamic range and this thing is just produces cinematic photos like nothing else I've ever seen! Focusing on the 5DII is and always will be an unreliable pain, though (even if just using the central point).
P.P.S
Nikon D700 in RAW! What an incredible sensor! Delicate highlight rolloff (and lots of information there); great organic colors and lowlight performance.