As LDAP account provider which is a best for the Nethserver, Windows 2012 AD ?
I am not sure if I understand what you mean. NethServer comes with 2 different account providers: OpenLDAP and Samba4 AD.
As another option you can use a remote OpenLDAP, Active Directory or Samba4 AD account provider.
What exactly do you want to know?
We have documented here, but probable we need to improve it.
What do you think?