so what you are telling me is that her Q buffs her teammates damage... well that would be broken if it buffed anything other than their autos for a single attack.
Her heal is not AoE, her shield is, if you are going to complain about a champion at least get things right please.
AoE stun... you make it sound like that is such a rare thing. Plenty of champions have that or worst (knockups) on their basic abilities and/or ultimates
Passive damage? like really? you really are complaining about a champion having a passive that does damage? well I guess we must complain about a lot of champions if that's the case since once again, only once and only after 3 casts.
AoE MS boost is pretty good but it's also the last skill Sona's usually max and it only really gets useful after putting about 3 points into it... so yeah, her E isn't even a factor until really late into the game and considering that Sona's late game is where she is supposed to be at her strongest I don't see much of an issue