Easiest way to find user authentication method on multiple F5s? BigIQ? API calls?

Im working on a project that requires finding the method of authentication used for logging in on quite a few F5 - what would be the easiest way to find that out? Logging in to the F5s directly is an option (and what was suggested), but it is time consuming and a huge pain in the butt. More than 50 less than 100. Just looking for suggestions! Thanks.