While you are correct that the duration of her aura increases for each ally she tags, you are still wrong. It does NOT refresh the duration or reapplication of the on-hit bonus/shield/movement speed boost for her allies. It only increases the duration that the aura persists, allowing her to tag other allies.
Though situational, I will stand by my argument that Thresh's shield still outclasses Sona's in the sense that it lasts longer, and provides far more damage mitigation straight out of the gate at the start of the game. That was the only point I was trying to get across. Ganks are what makes the power-level of the shield side-by-side comparisons situational.
The damage on Sona's ult is laughable, but she's a dedicated support not a hardcore mage. Arguing that the damage should be considered is almost redundant if you ask me, but I do see where you are coming from. Im only assuming that by "charge and hold it" you mean cast 3 spells, and hold the passive for the right moment to use her slow, which is where the Glitterlance point was brought up in the first place. Under that logic, the Sona needs to make an immediate decision while "holding" her passive to use it for a slow, damage mitigation (W) or extra damage (Q) in the heat of battle. This is all semantics, and we can go back and forth about this for days. Again, the comparison I brought up was to prove that Lulu clearly has more CC power than Sona, being able to use it much more frequently. My point still stands.
Again, you are correct about Soraka not being able to heal herself with her own heal-ability. The damage on Soraka's Q is not exactly impressive by itself, but it DOES heal her. There have been some Soraka posts on this thread that defend her in that aspect, so I will not even start on her. Again it breaks down to semantics. My point stands that the heal on both characters ends is intended not for themselves being in the support role, but for the team's benefit. Saying that she can't use it on herself is irrelevant, and the numbers still point out that Soraka's heal is overall better for the team. As far as the E damage goes, its all situational. You are right, the second half of the E is easy to walk out of. While you are walking out of it though, my ADC is pegging you with AA's because you are too busy avoiding E's silence and second half of the damage. Dont forget about that silence, friend. It's still indeed -- golden.
In terms of "laning," your statement that a Janna E can be negated by 1 Sona Q... Speaking solely of the damage threshold of the shield itself vs. the damage of Sona LANDING the Q bolt and AAing with the on-hit bonus damage, then yes. When I brought up the fact that Janna's E scaled, I wasnt implying that Sona's didnt. It was in response to how you just brushed off her damage bonus all together in your previous post. Are you implying that Sona still has more sieging power than Janna? That was my point, which you completely ignored btw.
I can not deny your points about Karma. You are definitely correct all around. Karma is all about immediate battle decisions. She has access to a lot more strength than Sona a lot earlier. Their power-spikes are way different. Thats all I was trying to point out there. As far as the numbers go though, side-by-side comparisons of their shield strengths is still not something to scoff at.
All arguments aside, I think I personally learned something here.
We have established that Sona's strength does not necessarily lie within laning phase, correct? It lies in teamfights. Why then is that the case when she is one of the squishiest champions in the game? If Sona's strength and power-spike arrives during teamfights, why is she so easy to kill? In a teamfight, targeting her first basically means you negate her as a champion all together because she is an extremely easy to catch. Her whole design under that philosophy is counter-intuitive.
Do you agree?