Give it a rest people. the WTF IS an important/prestigious tournament.
A player who's consider one of all time great but not winning at least 1 WTF would have a big hole in their resume.
Tier1(goat): Federer; Tier 1.5: Laver, Gonzales, Sampras, Nadal, Borg;
Tier 2: Lendl, Connors, Rosewall, Tilden; Tier 2.5: McEnroe, Agassi