Nadal 40 titles is a lot more impressive than any player who have won more. Mickey mouse titles is nowhere near as important as the slams and Master Series. Counting number of titles is misleading.
Tier1(goat): Federer; Tier 1.5: Laver, Gonzales, Sampras, Nadal, Borg;
Tier 2: Lendl, Connors, Rosewall, Tilden; Tier 2.5: McEnroe, Agassi