Then please call him the Greatest standing Men's Singles player of this era and not the Greatest tennis player of this era. In MTF, doubles and wheelchair will stand.Most of the names you mentioned are from other divisions. I was talking about men's singles since most of Nadal's achievements are in that division (moreover this is Men's tennis forums though you can discuss doubles also). There is a sister site named 'Tennis forums' for WTA stuff.
Since you have mentioned Djokovic and Federer, I would like to ask you who among the two leads the GOAT race (men's singles)?
Rafa surely has a stronger case than Federer and Djokovic but not stronger than Kunieda. Another men's singles player.