Kabuto also kept Itachi alive on purpose. Both Sasuke & Itachi needed each other to take him down.He defeated kabuto though ? He kept kabuto alive on purpose he could've easily killed him besides that I agree ... Mostly lol good thread
Most people put him up there because they are trying to justify EDO Itachi's power. When alive, his chakra level is barely above average at best, and he uses chakra taxing jutsus in rapid succession. He's like Kakashi, needing to rest after over exerting himself.
Edo Itachi is way up there, because he doesn't have to worry about running out of chakra.
Also, we can't judge Prime Hiruzen. We have less information on how strong he is than how strong Hashirama is.