Not sure that "security" should be the top reason for switching from Okta to AzureAD.
Also, as a "user" (in IT), AAD is a royal PITA to use, with stupid limitations, such as not supporting group hierarchies. And don't even get me started on the horrid UX of the Azure portal. I've never used Okta in any capacity, though, so I don't know if it's any better.
There's also OneLogin, Jumpcloud, or you can use Google Workspace and I think Azure AD too.