6. Byakuya Kuchiki
He is the head of Kuchiki Clan at the time and he possess the ability to dissolve his Zanpakutō into tiny pink blades and cut anything with them and that ability amplifiyes after bankai is released.
5. Kenpachi Zaraki
This guy is total monster who does not even use his Shikai yet but with bare sword and immense spiritual pressure, he was able to defeat Nnoitora (Espada no 5) but experience and control over one’s self is what he lacked.
4. Jushiro Ukitake
His dual Zanpakutōs Sōgyo no Korowai can absorb any attack and send it back amplified. Through his experience to access the situation, he makes his attacks more effective.
3. Shunsui Kyoraku
He is a careless and calm man with dual Zanpakutōs. He is the one who ultimetely took down Stark (Espada no 1). He is one of the oldest captains in Gotei 13 so he got plenty of battle experience.