Well, I think it's hard too choose, I mean:
Caroline Trentini isn't one of my favourite models, she's just a bit too plain IMO, but she's a great catwalker, bombshell and also seems to be hard-working.
Ana BB has a lot of fans, she is a great model for VS.
Adriana Lima is very beautiful. I don't want to comment if she's a good/bad model, but definitely she's one of the most popular Brazilian models.
I really really like Flavia De Oliveira. I know that many people think she's a stick, but she's a great HF model, which doesn't get as much attention as she should.
Raquel Zimmermann works in fashion business for soo long, she's a professional. And this face.... she's a beauty.
Alessandra Ambrosio is such a great VS angel.
I don't know so much about Fernanda Tavares, but she's very beautiful for sure. And her appearance at VSFS 2005
Isabeli Fontana is one of my favourite models. She's for so long, I think she's a supermodel material. She walked for every big designer for so many seasons now, she appeared at VS shows, she featured in many ads and eds (e.g. US Vogue).
She's very beautiful and I think she should be remembered as a supermodel, not a topmodel.
Cintia Dicker may not look as a "typical Brazilian", but she is so cute, and she makes redheads with freckles feel proud of their features I think
Bruna Tenorio is known for probably the shortest period of time from all these models. But she's walking in so many shows now and looks so exotic.
But, I guess, I will vote for Isabeli