You had to all in and Kill Sona. You couldn't trade, you couldn't poke, you couldn't do anything but ALL IN KILL SONA
The most popular supports right now.
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With the sole exception of Janna (and somewhat Bard) all of these champs have insane all ins.
All ins are only risky in lower level play where people just do them mindlessly, if you know where the jungle and mid lane are and you don't pick a terrible time to all in it's very safe to all in a Sona, safer than any other support since she can't really fight back.
You can also play Nami and Soraka against Sona quite easily, as long as you respect her range a little. They both have almost as good poke, better CC and better sustain.
Nami has poor burst.
Nami LV 18 damage (assuming 1 E hit[0 AA damage])
960+(180%AP)
Sona LV 18 damage (assuming Q power chord[0 AA damage])
878+(148%AP)
How does Sona have better burst than Nami? More to the point how is Nami not just a superior Sona? She has a stronger heal, hard CC on a basic ability, a better speed boost and to cap it off more damage.
Nami's conterplay is also arguably more dangerous than Sona's since you have to all in a champ with a threat of CCing you. Don't forget that Nami's should be held to the same standards as Sona.