She created a disaster in her kingdom, didn't want to fix it, and ran away from it instead, singing I'm Free song. Oh, she also drove away someone who told her problem and almost killed her sister with her creation.

How could Elsa was the least selfless? She stay away from peoples to keep them safe from her uncontrolled powers that can be injured them.
I don't see Tiana was selfless anyway, all she think just her dream to own a restaurant for herself.

All princesses are kind in one way or other, but I distinctlly remember Elinor sick on bed and Merida pestering her, wanting to know if the spell had worked.

Saving Eric was pretty much the only selfless and charitable action that came on her part other than saving Flounder from the shark though she forced him to be there when he didn't want to so that was her fault that he was in trouble to begin with.

Merida: Sneaking the dessert to her triplet brothers was kind of an act of charity or selflessness. Technically, teaching her mother how to fish and eat for herself was also an act of charity. Giving up her own selfish desires and offering to marry before she was ready as well as standing in between her father and mother (in bear form) were acts of selflessness.

Elsa: Listening to her father's advice and trying to stay away from others, so as not to hurt them, was an act of charity as well as the repeated attempts of warning to others in some way. Buying Kristoff a new sled and giving him a royal job (Royal Ice Master?) and giving Olaf the little cloud so that he could have life beyond winter/snow environments were also acts of charity.

I'm goin' with my gut on this one.

I wish...when Anna revealed to Elsa that her powers to build the ice castle had actually caused the blizzard... Elsa had not panicked, gone into denial mode, and shot ice into Anna's heart. Then, Elsa's repetitive denial to Hans that she "could do nothing at all about the blizzard" made me angrier. How come you can build an ice castle just fine "without love," Elsa, but you can't reverse winter? And how come you don't have enough self-confidence "to try to fix" the damage, Elsa? Why does your sister actually have to die in front of you, before you deem it necessary to do something?

I agree with audreygrace. Even then, she was more concerned about looking at Eric than reviving him into conciousness or calling for help for him. Not entirely selfless.