the slam finalists are underrated thus gets overlooked in here. It's not that easy and only a handful of players that have reach the final. If we include the finals Lendl is very impressive.
Tier1(goat): Federer; Tier 1.5: Laver, Gonzales, Sampras, Nadal, Borg;
Tier 2: Lendl, Connors, Rosewall, Tilden; Tier 2.5: McEnroe, Agassi