Roddick and Sampras probably had the two best serves of any players under the height of 6'4''. Who had the better serve? Roddick won 90% of his career service games to Sampras' 89%. I think Roddick had more pace and a much higher percentage of serves in, while Sampras had superior direction and disguise. Both had great second serves, Sampras' was a little more offensive but Roddick's was more reliable and pretty much unattackable.