for me moderate nat is better, less lag, better hitreg, but nothing spectacular, i'm still getting instakilled so often, i tried using wifi , but it doesn't make any difference for me maybe because the wifi router is too close with a good signal, i don't know i've to try out
opening the nat is just a horrible experience , not only with COD, i think it comes along with the nature of the equipment that the isp has, or maybe a too strong firewall, that add extra latency to packets that make you completely desync'ed from game servers
i've also experimented a strict nat with 4G, it's a bit better but again not a game changer
i've found an interresting article with a simplified explanation of the differencies of the differents nat types
https://serverfault.com/questions/208522/what-is-strict-moderate-and-open-nat