Verified answer

None of them can defeat him alone. The all have to rely on eachother to defeat him. The best group for defeating him would be: Urahara, Yamamoto, Yoruichi, Byakuya, Unohana and Isshin if he still had his powers up to full standard or Ichigo.

With his illusions only Yamamoto lives through the fight.

Without his illusions Aizen loses very quickly.

Urahara and Ichigo were able to beat aizen, i am sure these 5 would be able to beat him too.