I personally chose the Toa Metru/Hordika.Though the Inika/Mahri have to brave through many challenges, The Metru/Hordika had to brave saving the Matoran of Metru Nui (without them, I good portion of the Universe will die as well, hence the Great Disruption and Matoran Civil War), living with the fact for a while that they were not destined Toa, their savage selves as Hordika, and recieving heavy ridicule from Turaga Dume (then Teridax), claiming them to be imposters and fugitives of Metru Nui!Living with all those internal struggles during their life as Toa, in my opinion, takes true heroism.