SELECT query for fetching all user-created database names as a comma separated value

select 
  stuff( 
     (select ', ' + name 
     from sys.databases 
     where database_id > 4 
     order by name 
     FOR XML PATH('') 
     ) 
   , 1, 2, '') as DBnamelist;

DBNameList 
Database1,Database2,Database3,AdventureWorks,ReportServer$SQLSERVER,DatabaseName4