Part of this may depend on company policy, other parts on efficiency. In my previous job, we were required to use AD authentication for all apps, including SolarWinds so that password policy was maintained, and additional username/passwords were not required.
Where I am now, AD groups are far more efficient. We are a very large organization. We can set the permissions for the different groups. Teams generally see most everything, but Server teams only have permissions to change server items, network teams network items, VM teams VM items. We don't have to have different permissions per user, just per group. And the AD group membership is maintained by the teams or AD admins so we don't have to deal with that or with password resets.