WITH CTE_UsersPerEmployee (EmployeeId, UsersNumber) AS
(SELECT e.Id,
       COUNT(r.UserId)
  FROM Employees AS e
  LEFT JOIN Reports AS r ON r.EmployeeId = e.Id
GROUP BY e.Id)

SELECT e.FirstName + ' ' + e.LastName AS [Name],
       ue.UsersNumber AS [Users Number]
  FROM Employees AS e
  JOIN CTE_UsersPerEmployee AS ue ON ue.EmployeeId = e.Id
ORDER BY [Users Number] DESC, [Name]