Who picked Rapunzel? She's stated as an 17 turning 18 year old in the movie, and Ariel says herself she's 16.
IMO Either Merida, Ariel, Aurora or Mulan are the youngest. Merida and Mulan are supposed to be in the 15-16 range, with 17 really pushing it. Ariel we know is 16, same with Aurora. Cinderella, Belle and Rapunzel are all in that 17-19 window. Physically (especially for Merida and Mulan) and psychologically these are the ages that fit.

I don't know who keeps on picking Rapunzel, but I believe Aurora is the next youngest. I think it says in the film that Merida is 16, but I don't remember for sure

Did Jasmine go?! She's definitely older than Merida, to me Merida seems even younger than Snow White. Please correct me if I'm wrong, did they said Merida's age in the movie?

No idea what age Merida is, but Mulan and Ariel are both suppose to be 16 while Aurora becomes 16 in the movie...that would make her the youngest, even if she doesn't really look the part with her regal appearance

I think People are picking Rapunzel because she looks so young.

@fiina,Jasmine was 15 turning 16 in Aladdin, and I heard somewhere that Merida is 16

Or Merida, Aurora turns 16 in the movie, forgot about whether Merida is turning 16 or already 16, so I'm going Aurora.