I have always used Open Directory when Active Directory isn't available.
However for the first time I had an Open Directory go bad as a result of a major OS upgrade. I was going from Yosemite to El Capitan. A little command line work successfully restored the OD from a Time Machine backup. For years I've heard of Open Directory being fragile, but honestly this is the first time I've been stung by a broken OD. Things that easily break are things I want to avoid
I generally have sites dominated by Mac OS clients, with a few Windows clients here and there. Also Mac servers, and services & devices that support LDAP. The JSS for one. Some things will bind to Open Directory LDAP, some don't. Authenticating network printers would be nice.
I've been quite successful with pGina for authenticating Windows systems, but it is a rather clunky solution and leaves out things like printers A hosted directory service seems appealing, at least from what little I know about it. OneLogin seems rather expensive to me however. Virtual machines are on the table.
Anyway, I've heard mention of other directory services. OneLogin is one that stuck in my mind but at around $8.00 per month per user, that seems quite expensive. Are there others? What are your experiences with Open Directory and Active Directory alternatives?