6D + Canon 50/1.8 or D600 + Nikon 50/1.8? Help me decide.

The world really does NOT look like 14 stops DR. Not through our eyes, anyway. Stating that is.. a lot besides the truth. Take a high DR shot against the light at noon in summer. You will have awful light, unattractive scene, subjects in shadow. A high DR scene you should never have taken.

Now flatten the tonal curve as much as you can (turn down the contrast in your RAW converter). You will not be able to get 12 stops of DR into the image that way (at least not with the RAW converters I have used), but more like 10 stops. The image will look more flat than it looked like in real. In real, we do see shadows, in real we do see super bright spots we need sunglasses for to not have our eyes have trouble. In real, our eyes adjust going from the darker parts and going to the bright light, and in real we do notice that very obviously.

It is not true to state that compressing more stops into the low DR of screens and even lower DR of photo prints makes images look more realistic.

One of course can choose to use a bigger range, HDR has its uses. But lifting shadows from the low information density dark side of RAW is not optimal. Then it is smarter to shoot 2 or 3 frames with different exposure times, simply for the better gradations in the former darker parts.

Anyhow, the DR from both cameras is more than adequate. If it was not, on one would ever contemplate taking an ISO 800 or 1600 photo with the D600. And if one truly is a shadow hater, one can still pull the shadows from a 6D several stops (I never get why one would want to do such a thing, though).

I happen to have a camera that DOES lack DR from ISO 400 and up. But that is beside the point(s)..