Lana does a freaking fantastic job of keeping Regina from becoming cartoon evil. Regina/Evil Queen could easily have been a laughable character, chewing scenery and coming off as a joke, but honestly I find Regina Mills' cold, quiet vengeance terrifying. The way she confronted Mary Margaret in the cell, told her she knew she was innocent of killing Katherine but still revealing in the fact that MM was going down for a crime she didn't commit was chilling.
Maybe I read into these things too much, or maybe Lana is just a fantastic fucking actress, but I find that as an example of when her lashing out is because of the pain she feels and her fear of being rejected by her son.
I totally get people just flat out hating Regina, but as a character I find her fascinating, mesmerizing and awesome. And Lana gives those of us who want to delve deep into the psychology behind her evil plenty to chew on and I love the actress for that. I love an actor/actress who really thinks about their characters motives and insists that there be motives. It challenges the writers because I feel like she won't let them get away with making Regina do something just because they think it would be cool or to fit the story. Lana seems like she will find a way to make it fit the character first. I love actors who are protective of their characters.
And yes, I'm pretty sure I have a girl crush on her so I'm Team Regina no matter what she does. She could pop the heads off puppies while dancing across the backs of small children and I think I'd still love her. Especially if she did it with that low, simmering loathing that Regina does so well.