Hmm, this is a really hard one. I'm gonna go with Pocahontas because I feel what Elsa really want's most in life is to free. To let it go, lol.

Of all the Princesses, I feel like Pocahontas fully embraces the spirit of freedom. Jumping off cliffs, painting with the colors of the wind, etc. Elsa would really envy that and I think she would use Pocahontas' movie a method of catharsis, especially when she's younger and in her room all the time.

In the end also, no matter how uncertain she might be at times, Pocahontas is always in control of her own story. I feel like Elsa would really aspire to be like that. In the end Elsa just wants to control her life.

I think because she could relate to Rapunzel, ya know, being locked up her whole life, having a special ability, and finally becoming free. Or B&TB

Given every body thinks she's a monster. She'll probably enjoy Belle too.

Idk

She is as carefree as Ariel.