Using View filters for tenants in SQL-Server 2008
I'd use SUSER_SID for this reason:


SUSER_ID is the principal_id column in sys.server_principals
SUSER_SID is the SID column in sys.server_principals and be generated by Active Directory (Windows login) or SQL Server


If you move the database to another server


then SUSER_ID will almost certainly be different.
SUSER_SID will be the same for Windows logins, but can be made the same for SQL logins by specifiying SID for CREATE LOGIN.