AF tacking 5DMKIII & 1D MKIV
Sorry no 5D Mark III, but a 1D Mark IV and 1DX. Yes the 1DX is better, but the Mark IV is very good.
I can only estimate but the 5D Mark III shares 95% of the AF function of the 1DX, so it should also be better than the Mark IV. Personally I would take the Mark IV, it is one great camera.