Orochimaru isn't the strongest guy

I believe that the 4th is the strongest ninja that has been introduced so far, even though he is dead. Itachi might not be stronger then Jiraiya doesn't rely on Juutsus as much, which means Itachi can't read him as easily with his Sharigan, it's most likely like a rock paper scissors situation, the ninjas are probably strong in different points.

Oro definitely isn't the strongest.

There has to be other stronger nins...most of which we don't see but i guess they would be supposedly part of the Akatsuki organization.
I doubt that itachi and kisame are the only ones that are strong within the org.