I'm gonna post the results in an article, so explain yourself if you can and vote the one that you think is the closest, not for your favourite pair.

Maybe, they were close in the past for sure and they work in TTS together. At least during their Twinkle concerts it was still clear they had a bond, I don't know about now though.

She's closer to Sunny because she's once/twice(?) picked Sunny as her bus seatmate. And Tiffany picked Yuri :/

this may sound mean but Tiffany stopped being "close" to taeyeon after Taeyeon's "scandal" came out. Now she is around everyone but her.

Taeyeon has sunny and what it seems only

Sunny, Tiffany and Sooyoung are by far, her closest friends in snsd

Tiffany or Sunny, since I'd say that they're both really close to her and she's said that she considers them to be her best friends.

Sunny!!

I prefer Taeyeon with Sunny, but Taeyeon definitely seems more closer to Tiffany in my opinion. They have been in TTS together, so they spent more times together. They were dorm mates pre debut for a really long time...(I think 10 years or something, I forgot) and they have SOOO much moments. On TTS, it shows rhat they are pretty close in my opinon.

sunny

yep