So, we've seen how Soraka has faired with these past couple nerfs.

I don't agree with your aggression, but I certainly DO agree with the sentiment.

Soraka is actually fairly strong. I wouldn't call her "OP," since that implies there's no counterplay (and she has plenty) but she's definitely viable. She has plenty of damage and sustain (I'd go so far as to take blue pots instead of red at spawn) and can stop ganks with a well-placed Equinox. Her one problem is her lack of an escape-- if she gets flanked, she's a walking corpse. However, this was always a problem for her. It's the weakness necessary to balance out her strengths.

What the Farmer may be seeing is that she isn't any good on her own. She's worthless at low MMR because you can't trust your ADC. A champion that relies entirely on aiding their allies (rather than harming their enemies) will almost always have this issue; that's why mage supports are so popular. They can have an impact even if their lane partner is playing badly.

Janna and Sona are kind of in the same place. They rely on their teammates, which renders them weak when their allies are unskilled. However, at mid-high MMR they have a huge amount of potential.

She was fun to play before the nerfs. :(

People used to talk about her on the boards a lot, actually. I think her new kit is a huge improvement on what it was. Before they nerfed her out of existence and Sona replaced her.