1d mark iv instead of a 5d mark iii

I am sure someplace around here this has been discussed but after a few pages of searching I gave up. Assuming a 'like new' 1d mark iv is the same price as a new 5d mark iii which would you choose?

All of my glass is 'L' series and I am looking for something for out doors sports. Softball, baseball, soccer.

Any and all thoughts are appreciated.