For Prêmio Brasil Olímpico, which will take place at December 18th, the nominees are:
Men
Gabriel Medina (Surfing)
Isaquias Queiroz (Sprint Canoeing)
Pedro Barros (Skateboarding)
Women
Ana Marcela Cunha (Swimming)
Ana Sátila (Slalom Canoeing)
Marta (Football)
Isaquias won the award 2 times, so I'm guessing they're going with Medina (first time nominee) this time. Among the women, Cunha won before and is nominated almost every year, while Sátila achieved her second nomination in a row. Marta is a easy pick because she never won before - which also would be the first time a footballer (man or woman) wins!
There's also a thing called Atleta da Torcida, which basically it's a popular vote award that strangely enough doesn't include some of the nominated athletes above. The nominees are:
Erika Miranda (Judo)
Bruno Rezende (Volleyball)
Arthur Zanetti (Gymnastics)
Henrique Avancini (Cycling)
Gabriel Medina (Surfing)
Ágatha/Duda (Beach Volleyball)
Letícia Bufoni (Skateboarding)
Bruno Fratus (Swimming)
Marta (Football)
Eduarda Amorim (Handball)
I guess Medina wins but who knows. If he (or Bufoni) posts something about this on their instagram accounts, they can easily win, but right now Avancini of all people has more than 80% of the vote (most likely because he said something about the award in his social medias). I voted for Erika. Anyone can vote here.
Finally, the brazilian committee also picks the best in each Olympic sport (for winter sports they simply divide between "ice" and "snow") and all these athletes have their moment at the ceremony. The list: