From PJO/HoO, either Piper or Calypso. Piper's seriously awesome, I love her entire arc and how she gains confidence and grows into her role. As for Calypso... I think Leo and I just share a type?? I like scary girls who are good with their hands T_T
From Magnus Chase, I loved Magnus as a kid and I still love him now. He's the best.
Kane Chronicles didn't really stick with me since my sister liked it more when we were kids, therefore I had to be vehemently indifferent to it. I'll reread it in future.