Right now I am in the market for the "perfect shoe". I have tried the Ryka Affirm (oooo, yuck!), and the Freddy (don't now the model), but it was too big (usbodyware.com no longer will carry them, so they will never have my size). I have returned the Freddy's and have exchanged for Otomix. The shoe I've picked is on usbodyware.com's website (it's the one that comes in black or white). If this one doesn't work, I'll try the more colorful Otomix at usbodyware.com. If that doesn't work, I will order the Ryka Rhythm II.
Sheez! Nobody around where I live carries a good aerobic shoe that I can try on, so I have to order them.
I currently use a walking shoe for aerobics (causes a "burn" in the soles of my feet up in the toe area), and a running shoe for the weight work (it's just a REALLY comfortable shoe, but hurts my legs and ankles if I use it for aerobics). If you can find a comfortable crosstrainer, I think that would be your best shot for aerobics.