The problem is in a discussion like this, is that the elite players that won grand slam titles will receive most of the nominations. However in any generation, many of the lower ranked players are just as fierce competitors as the big guns, it's just that they are not as talented.
For instance Nicolas Lapentti (who won 16 matches in his career that he faced match points in) was just as big as fighter as Nadal has been. It's only that Nadal is the considerably more talented player. While Nadal has been displaying his fighting spirit in grand slam semi-finals, masters series finals etc, Lapentti was more often displaying his fighting spirit in smaller ATP events.
Similarly Felix Mantilla in the 90s was just as big a fighter as well reknowned warriors and grand slam champions like Muster and Chang. I mean the guy twice won matches that he saved 9 match points in.
That same logic is true as you go further and further down the rankings.