I believe the IRR method is showing how much money a company actually gets to keep if it invests in a certain opportunity. Smaller investments will sometimes attract managers more than bigger investments if they only look at the IRR. The higher rate of return immediately may be more of a bragging right than actually making more money for the company in the future. Payback Method seems pretty general and inconclusive, I cant imagine financial experts relying much on this method. Net Present Value seems to be good to use just to see if the company will lose or make money when its all said and done.
Initial Response attached.