We previously used Microsoft's Active Directory.

Like OAM no, we use workaround web services with RSA.

I have used several products in the category of access management. In my opinion, other products — and in particular SiteMinder — are more reliable. I like the SiteMinder product as it is also simpler also to install and configure than Oracle Access Manager.  

Previously I did not use any other solution.

In my experience, clients did not have a previous solution. The idea of the installation was to provide a solution which did not previously exist and make managing sign on less complicated.

Previously, we were using the AWS based product and Okta.

I've used Symplified, SiteMinder in other shops. This was an Oracle shop, so there was no discussion on which solution was best.