This is an interesting topic, but the REAL question is what colour are (insane) Bionicle brains? (Incidentally, I like to imagine that Matoran and related species have flesh tinted in their eye colour, since I have a headcanon about Matoran having a sort of elemental energy conducting "blood" in the same colour as their eyes, but there's no real evidence for that in canon.)
It was a very hard decision between Crimson Typh- er, Vermillion Tempest, The Days They Were Needed, Fatal Wound, Charge, and Attak on Bionicles, but I could only choose one, and my vote went to no. 6. Good job, all of you!
Number 2 was generally mediocre, number 3 was confusing and uninteresting, number 4 was graphically unimpressive, and number 5 was sexist, racist, and cissexist, as well.as being uninteresting and ill-structured... but even if that hadn't been the case, there's only one I could have voted for. BAC for the cup!