I gave one reply on another tribe, which comes down to basically this: depends on your size.

Go out, try on as many as you can. Spend no less than 2 minutes running in place with it on to find out if it will work for you. Or if you're going more for looks than non-bouncing, dance around in it in the dressing room… see how well it lets you move, how well you move in it, etc.

If you're big, don't be conned by "one size fits all." (And I mean cup size, not body size.)
If you're small, don't be afraid of racerbacks or underwires. They may be what you're looking for.
Decide if you don't want uniboob, or if you don't really mind it.

it's a great idea to get a proper fit, but take what the person doing the fitting says with a grain of salt... I have been wearing a 32 DD since high school, except for a brief time when I was a 34 DDD towards the end of pregnancy and during nursing my kids, and each time gone back to my original size... The gals at nordstrom and macy's were spot on, very helpful, whereas the victoria's secret gal was pushy, and insisted that I squeeze my boobs into a 34 b or c so that I would buy their most expensive one (victoria's only carries and extremely limited selection of small band/large cup)
For more affordable options, Target offers a good selection in their gilligan o'malley line....
and for maximum support during class, I love layering a simple uniboob sports bra or shelf-bra tank over a comfy unlined/unpadded underwire.
My other most comfortable bra was a playtex 18 hour cross your heart, the kind that comes in a box, great support without an underwire, and gel padded straps. Mine got stretched out with my last pregnancy, though, and haven't been able to find a new one yet.

I haven't tried it yet (it's in the mail) but the Geisha Moth Incognito is supposed to be a sort of bra/dance top. You might want to ask over on the Geisha Moth tribe about peoples experiences with it.

I have a shock absorber - I have to give myself an extra couple of minutes in the morning if I want to wear it, because it's a bitch to get into! But once on it is very supportive.