Something between these cameras?

I'm looking for a pro camera, i want something better than the canon 5D mk III but not as good as the Canon 1D (would like it to be canon as i'm switching from nikon) So something inbetween the two would be good

I don't know

I don't believe there's anything in between.

Why on God's green earth would you want to replace every piece of kit you own?

A Canon will do nothing your existing Nikon can't - and Nikon do full-frame bodies too - if your pictures suck with a Nikon, they'll suck just as hard on a Canon.

There isn't one in between.
The Canon 1D is their absolute top of the range and the 5D is the next one down.
They do a 6D full frame sensor camera but that's a lower spec than the 5D.
Go for the 5D; it's a fantastic camera.