Testing for inequality in T-SQL

These 3 will get the same exact execution plan

declare @id varchar(40)
select @id = '172-32-1176'

select * from authors
where au_id <> @id

select * from authors
where au_id != @id

select * from authors
where not (au_id = @id)

It will also depend on the selectivity of the index itself of course. I always use au_id <> @id myself