Sampras was so good, but injuries were tough on him. He would have won 5 or so more majors if his back wasn't shot. I still think he was the best on grass ever with Fed right there behind him.
As for all time, I hate to say it, that's where Fed beats Pete for "best ever." All around championships have to put Fed over Pete. Impressive what him and Nadal have been able to achieve, and playing each other a lot head-to-head.
I don't think Federer has a French Open title. But Nadal has at least won ALL of the major titles. He's got to be in the discussion for best ever.
Still, Pete did marry Veronica Vaughn though. That alone could make him the best ever.