Dude, the fact that Morgan starts in basically Super Hard mode while Ainz starts in Easy mode alone is enough to decide which one is better ruler.
It's like deciding which one is better Simcity player when one has handicaps on their land map while the other one has advantage modifier instead, and the former still doing well despite said handicap
It's primarily because Bellows and Pen are the biggest Overlord wankers I have seen. Not even fans can pretend Ainz is some great ruler when most of the time, he literally gets bailed out by luck or just overpowers people or the other rulers being such shits that Ainz somehow looks better by default.
Like the VS. match is already retardedly fubar(like every time Overlord is ever put into a VS. match) but the ruler shit is 100% a no brainer.