I agree with Guy, that the body is not inherently as important as the lenses and the back. But the back is freely interchangeable with many choices (you could pick any of the options in the poll, and change the back afterwards); whereas the lens range is not. I rank the lens range as the most important factor. But since the body determines which lens range can be mounted, that indirectly makes the body important too!
Since I have (and really need) such things as a full-frame 645 fisheye and 200/2.8 telephoto, there's only one choice for me - the Mamiya/Phase 645AFD/DF platform, mainly with manual focus lenses.
The Rollei 6008AF/Hy6 comes close for fast lenses etc., and the bodies are wonderful, but it's a lot more pricey as a system.
But I dispute one aspect of the poll: I would not pick any
of the digital backs listed (IQ/Aptus)!
That restricts the whole poll to Dalsa sensors only, and they are just too noisy and restrictive in long exposures. Give us some Kodak options (most P+ backs, Hasselblad CF, Sinar 65LV, etc.) please!