Sampras' was the best in all aspects of serving
- consistency over long period
- management and change ups
- backing it up with rest of his game
- and so on
It was proven time and time again for over decade, we witnessed how deep
Pete's serve was in every aspect listed above.
In terms of sheer potency, some people say Krajicek's and Ivanesvic's were
the most devastating.
And, please, somebody drop Wayne Athurs from this thread.