SQL SERVER – Best Use of EXISTS Keyword (Performance hint)

In below two scripts I have  used the Use of = and IN operator in 1 & 2 Query  and in Third query I have used the Exists Keyword for checking the performance issue and when I seen the Execution Plan and the outcome is that Use the of = operator or IN operator is less better than use of EXISTS Keyword.

Run the below script and See the Execution plan.

USE AdventureWorks

GO

--1) use of IN operator

SELECT * FROM HumanResources.Employee E

WHERE E.ManagerID  in ( SELECT EmpAdd.EmployeeID

FROM HumanResources.EmployeeAddress EmpAdd

WHERE EmpAdd.EmployeeID = E.ManagerID)

GO

--2) use of = operator

SELECT * FROM HumanResources.Employee E

WHERE E.ManagerID  = ( SELECT EmpAdd.EmployeeID

FROM HumanResources.EmployeeAddress EmpAdd

WHERE EmpAdd.EmployeeID = E.ManagerID)

GO

--3) use of exists Keyword

SELECT * FROM HumanResources.Employee E

WHERE EXISTS ( SELECT EmpAdd.EmployeeID

FROM HumanResources.EmployeeAddress EmpAdd

WHERE EmpAdd.EmployeeID = E.ManagerID)

GO

Result: (Snap Shot of Execution Plan)