It's like musical chairs with these three. Where one/two excel and the other two/one fall short. Merida and Anna have developed personalities but one is just Rapunzel 2.0 and the other's just a melting pot of Renaissance princesses. Merida and Elsa are iconic characters but it's hard to distinguish them from other princesses for different reasons, and they're prime examples of "style over substance".

At the end of the day all three of them and their movies are just a result of Disney trying to way hard too make them feminist and relate-able heroines and they're all just middle fingers to the older princesses in some way or another.

I think Merida is pretty unique, and Elsa's personality development i'm kinda on the fence about.
As far as Ana ... I don't see anything special or iconic about her whatsoever D:

also Anna's character isn't iconic enough.

I might like her a lot, but it's the truth anyway. She's just another strong 90s tomboy.

Maybe the Elsa one too, but this one much more.

Mostly the Anna one though. I don't see what's so special about her personality.

I disagree with the other two.

Nobody said Anna was special (which is a shame, because she is- how many heroines nowadays do you see being so stubbornly forgiving, loyal and unconditionally loving to someone most people would resent and not forgive for their coldness?).

She has Ariel and Jasmine's biggest flaws without having her virtues. She doesn't have admirable traits to me.

Her personality-wise is a mix between Ariel's and Rapunzel's traits. She's also has been overshadowed by her sister. Merida's behavior and attitude is a lot like Jasmine's and Ariel's, but she still has her own uniquess. I disagree with Elsa one.