I haven't seen a thread about this, but, i'm gonna list the shinigami(pure, non vaizard from) in the order i (think) is the strongest.
#1 captain yammamto } (tie for first in my view)
3.The two dual sword guys,
4. Kuchiki byakuya
5. Soi fon
6. Ichigo kurosaki(without hollow help)
10. Fox guy
This is based on battle ability rather than the ability of zanpakutos, Which in that case i would have ranked the science guy, soi fon, urahara, kuchiki byakuya as the top ones with ability.
I also wanna rank the vaizards , hollows, and arrauncar, but... i don't think there are sufficient data on them. But if anyone wants to? or wants to supply their own lists go for it :)