1d mark iv instead of a 5d mark iii

Another thing to consider is that the Mark IV is also more weather resistant than the 5D Mark III.  But you can't beat the megapixels of the 5D Mark III (assuming that you are going to make the huge prints that require the extra resolution... for me, never printing bigger than 13x19, the Mark IV is fine and I can always tweak the image if I need to print bigger).