Hate to break your circlejerk, but...
As a sona player, I don't feel that she needs a stun. Her early-game strength lies is her poke and sustain, and good mobility for moving around the map to ward and what not. I think if you added a pre-6 hard-cc, she would become way too powerful. I'm actually quite happy with her current state, although a slight buff to her stats wouldn't hurt. :)
Sure a stun would be nice, but a good Sona player can still be very useful, especially if you build utility over the meta damage build
If you give sona another stun, you will be opening up the gates for people to whine (yet again) about how strong she is.
Stop trying to make every champion the same. Let them specialize in different things, please.