tennis

Roger Federer is the most successful male tennis player in history.

Here's the list of notable men's grand slam titles winners:

Federer: 14 (career grand slam)
Sampras: 14 (missed French)
Emerson: 12 (career grand slam)
Laver: 11 (career grand slam)
Borg: 11 (missed Australian and US)
Tilden: 10 (missed Australian)
Agassi: 8 (career grand slam)
Perry: 8 (career grand slam)
Budge: 6 (career grand slam)

You could debate better career of Sampras vs Emerson, or even Sampras vs Agassi. Is 14 total better than 8 if you couldn't win on clay?

But what you can't debate is that Sampras' 14 is better than Borg's 11 and that Federer's 14 is the best of them all.

On the women's side:

Margaret Court: 24 (career grand slam)
Graf: 22 (career grand slam)
Moody: 19 (missed Australian, did not participate)
Evert: 18 (career grand slam)
Navratilova: 18 (career grand slam)
King: 12 (career grand slam)
Serena Williams: 10 (career grand slam)

It's a lot more cut and dry. Also, Margaret Court is a good name for a tennis player.