Is this poll really necessary? In this case, unlike the sexy poll, it's not all subjective. Hyo really is the clear frontrunner in all aspects. She was the ONLY female trainee to be in the boys' dance classes.
The rest does have subjective bits, but it's basically tier-based.
I do believe Yuri firmly has 2nd place locked down. She has full control over all different styles, but where Hyo beats her is in power and stage presence.(And training in additional styles, since Hyo began with ballroom, and we know she learned tap dance at WDS.)
In the next tier you have Sooyoung, Yoona, and Jessica WHEN SHE'S NOT BEING HER LAZY SELF
. This tier is for people whose base level is solidly comparable to top dancers in other groups(Hyunaaaaaa...) but may not be able to do expressions across the board quite as well.
Sooyoung and Yoona both are too skinny to have the right amount of heft behind their moves sometimes, so Yoona's strength is in precision moves as her ITNW concert dance battle solo highlighted. Sooyoung, as Jaewon noted in his analyses, obsesses over details and so often has a slightly better level of "gangsta-attitude" expression than Yoona, but she's not quite as precise AND I CAN'T FIND GOOD FOOTAGE OF HER DANCE BATTLE SOLO ANYWHERE
but cameras tend to miss her footwork which is one of her strengths. However, Yoona is getting much better with her facial expressions and will sometimes be better than Sooyoung on the sexy routines.
Jessica has the ability to be in Dance Line, and she kinda was early in SNSD's debut, leading the Chaotic routine with Hyo and such. And of course that preview belly dancing video.
As of now she's also fallen into "too skinny" world.
But we've never seen Jessica dancing at full potential in any of the power routines so I can't for sure know how I'd rank her at full potential. But in both Laarbasses and her MTV solo of Chaotic she's been a bit flaily with the arms, not as precise with the positioning and posture.
In the next tier you have Seo, who dances as solidly as Sooyoung and Yoona, but lacks that additional layer of emotion needed.
Then you have Taeyeon and Jessica Lazy Ver. If you watch a lot of the routines where they subunit into threes and such, such as Crazy in Love, the RDR intro dances, and ITNW remix, Jessica often gets groups with a combination of non-Dance Line 4 so she can happily half-ass stuff and not get criticized too much.
But she'll get the moves right, even if they're half-assed. Both in Crazy in Love and the GDA RDR intro she was the crispest one in her grouping, as well as the only one not to make a mistake.(Even Seo screwed up Crazy In Love)
Just as Jaewon noted, Taeyeon will make up for her lesser technique by expressing the hell out of it. Dancing Taeyeon is at her sexiest. Also don't forget in the MTV solos Taeyeon did Break Away right along with Original Dance Trio HyoYoonYul, and nailed it.
Last tier is Tiffany and Sunny. Sunny has good sexpressions but is kind of inconsistent about them. Tiffany ROCKED the awesome DC RDR intro but that's a rare case for her.
And basically this is all in-line with Jaewon's own analyses.
That boy loves Hyo so much, she's definitely one of if not his favorite students OF ALL TIME.