I would go Bellona aswell. Even though i have not played her she is a PAIN to Vs because of her damage potential and tankiness. I have played Athena and i dont like her. Yes she's one of the top Guardians but i find her boring, weak and hard to play for some reason. Bellona can Solo, deal damage, hold a lane, pretty much everything and anything, Athena on the other hand can be a great support and can take a hit, even deal damage if built. At the end of the day its what you like, if you like to Support then Athena is the way to go, if you like to Solo and deal damage and annoy the hell out of the enemy team, then Bellona is a great choice