You have your top tier villains like Ares and Circe that seem more then powerful enough to give Diana real problems.
Cheetah and Silver Swan seem more like emotional threats then physical Threats (I never felt Cheetah would actually challenge Diana much if she wasn’t holding back). Then you have other villains like Giganta that Diana usually trounces with only moderate effort.
I’ve always felt the Angleman and Dr. Cyber should be bigger threats then they usually depicted being.