Zaheer. IIRC, he beat Super Korra.
He evaded with flight while she was dying from poison. The one time he faught a bender/fighter on Azula's level (Tenzin), he got trashed.
That could just be a feat for Tenzin. And the location here is much more suitable for Zaheer than it is for Azula.
So you think Zaheer and Tenzin are > the Avatar State?
Not really. Could Zaheer even fly when he fought Tenzin? If he could, he didn't fly once for some reason. I don't see Zaheer doing well against Avatar State without his flight. His flight is a a huge advantage.