Nole still has some work to do. He has been so consistent on all surfaces since 2011...either he's a champion or a runner-up is a testament of domination. I know some people(except many old-timers) will argue for him being in the top 10 greatest of all time.
Tier1(goat): Federer; Tier 1.5: Laver, Gonzales, Sampras, Nadal, Borg;
Tier 2: Lendl, Connors, Rosewall, Tilden; Tier 2.5: McEnroe, Agassi