What I really like about her is that she's one of the first female protagonists in Disney to not be naive and act like some 'damsel in distress'. That is, she is quite capable of taking care of herself and doesn't need some mighty man to do it. Also, I admire her resilience and fearlessness in a lot of situations, like when she was fighting Shan Yu. She's also really selfless and isn't spoiled or pampered or super duper rich. And I like how she has the guts to defy her country's traditions, instead of just keeping her opinions bottled up.
She may be stubborn, fiery, and a little rude at times, but that's what makes her a brilliantly written character. This princess puts forward the fact that nobody is perfect and that you can't force people to follow a certain tradition e.g. Being betrothed at an early age. In other words, she is pretty similar to Mulan. Her tough, tomboyish and feisty attitude is also another big difference from the other Disney Princesses; at least we have someone who isn't afraid of forests or falling into water, and likes archery! Like Mulan, Merida isn't likely to act like a damsel in distress and allow some totally random prince to leap forward and rescue her. Female protagonists who can defend themselves are so much better than the ones who cannot. I like how she is also shown to have a soft side; she really does care about her mother even though she doesn't see eye to eye with her.
Okay, I'm not going to go into a lot of depth here since my reasons for picking her is the same as the others. Tough, resilient, spunky and willing to try new things, she also isn't the type who lets the men do everything for her. I was laughing really hard when Moana grabbed Maui by the ear and started snapping at him to listen to her. Again, she doesn't hesitate to defy traditions, even if her Tribe doesn't approve of it.