Confusion in dynamic query MS SQL 2012

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SQL

Microsoft

SQL-Server-2012

Hello,

I am stuck between dynamic query and simple query.
From Google I got the solution for simple query with dynamic condition in where clause.
But now I have one confusion for this simple query which have dynamic where clause.
See below details.

I have below a table and two queries in SP.
Here assume that table have million, billion rows.

SELECT ts.studentId, ts.studentCity,
 ts.studentState, ts.studentCountry,
 ts.studentPhoneNo, ts.studentEmailId,
 ts.studentAddress, ts.studentName FROM dbo.tblStudent ts

Data is like

studentId	studentName	studentAddress	studentEmailId	studentPhoneNo	studentCountry	studentState	studentCity
1	xyz	xyz address	xyz@xyz.com	123456	country	state	city

1)

DECLARE @studentName nvarchar(100)
DECLARE @studentEmailId nvarchar(100)

If(@studentEmailId <> '')
BEGIN
       SELECT * FROM dbo.tblStudent ts WHERE 
       ts.studentName = @studentName
END
ELSE If(@studentName <> '')
BEGIN
       SELECT * FROM dbo.tblStudent ts WHERE 
       ts.studentEmailId = @studentEmailId
END
ELSE
BEGIN
       SELECT * FROM dbo.tblStudent ts WHERE 
       ts.studentEmailId = @studentEmailId AND ts.studentName = @studentName
END

2)

DECLARE @studentName nvarchar(100)
DECLARE @studentEmailId nvarchar(100)
SELECT * FROM dbo.tblStudent ts 
WHERE 
ts.studentName= COALESCE(@studentName,ts.studentName) AND
ts.studentEmailId= COALESCE(@studentEmailId,ts.studentEmailId)

Here also assume that in some case second query have multiple condition in where clause.

My question is which one is faster and better to use?

FYI: I am using MS SQL 2012.