Then in that case....I say mab is good!...since most are gonna call her evil! EVIL I say....lol

From a welfarist perspective, and assuming that being overrun by outsiders is detrimental for human (or sentient (or in the DV (soul-having (or insiders as opposed to outsiders))) welfare, this is a justifiable position too.

We really have to consider this from an in-universe-perspective, and for this we first to have to determine what kind of fiction we are dealing with. In many fictional works, there exists absolute good and evil. An example would be the Star Wars Universe. As long as a Jedi stays on the light side of the Force, it isn't really important how many people he maims or kills, how much corruption she enables or how many atrocities he commits. He or she is by definition a good guy.

I am not sure whether the DV falls into this category.

Form the author, I got the impression that the question is - in the DV - centered around the preservation of free will, which conveniently appears to be a unique property of humans and select ex-humans. If we restrict it to that, then Mab is evil simply because she acts evil in trying to subvert this, regardless of any greater utility she may achieve this way. She has no qualms about using humans as means to an end.

I started to write a fanfiction in the DV mostly to strengthen my precarious grip on the english language. And because I really don't want to mess with established characters, I placed it in Europe, where Harry probably never will stumble over the places where my original characters interact with unofficial offshots of vampire courts, Sidhe and other dregs. That makes it an exercise in world building as well.