Just trying to demonstrate what would actually be something special, that players might actually trade some losses for.
You have the argument all wrong. Federer and Nadal won the same number of slams in their respective years, so we're not talking about if players would trade slams for more wins. In fact Federer actually did better than Nadal, making all four finals, guess how many people have done that since Laver? You're argument is that winning on three different surfaces, is somehow superior to absolute dominance. That's the crux of the issue, McEnroe and his FO is a completely different argument, particularly given there were in practicality only 3 slams during his peak. And how exactly are you differentiating between a fan and players perspective, given, I presume, you are the former, and not the latter?
And who exactly has pulled off what Federer or Mcenroe did? Nobody, not even Laver. Of course the tour was different then so there is no real way to compare. Essentially you're argument is that winning on three different surfaces is superior to utterly dominating the tour on an absolutely unprecedented level, well of course there's going to be disagreement.
Anyways, not saying you're right or wrong, this is obviously all utterly subjective, I am simply offering a different perspective.
As a fan, I think Fed's best season (take your pick which one) and Nadal's best season (2010) are both worthy of consideration as the best since Laver. I'm not excluding any other player's seasons from consideration either. Pick whatever season you like best, and you will get no complaints from me.
My main point was that if I was a tour player, I would personally choose Nadal's season, because it would come closer to what MY dream season would look like.
It's a relatively small number of players that win even a single grand slam during their careers. If we gave those players a chance to choose a dream year, I think Nadal's 2010 would get some votes. I'm confident that a fair number of players would covet a slam win on each of the three surfaces, and that some would pass on Fed's best season in order to get that combination.
Alternatively, if we asked players that had already won grand slams, I think it would depend on who you asked. Even the greats would love to have the trophies that are missing from their collection.
I think Mac would love to have a FO title, Borg would love to have a USO title, Lendl would love to have a Wimbledon title, etc. If Mac had to trade his '84 season for Fed's 2006 or Nadal's 2010, I believe he would pick 2010, just to get that FO title in the deal. If Borg had to trade, I think he would pick Fed's 2006. I think Borg would love to have 2 quality hard court slams to match the bevy of grass and clay slams he already has. Yes, the AO wasn't relevant in Borg's day, but it was fully relevant when Fed won it. The point is that Borg lacked hard court slams, so Fed's season would be a better "trade" for him, IMO.
I realize that other factors can come into play besides just what slams were won in a given year, but I think the slams would weigh VERY heavily with most players if they were asked to choose the "better" season. From the perspective of Fed or Nadal, I don't see much reason for one to covet the other's best season. I'm sure both are thrilled with their best seasons, considering both have won all 4 slams anyway.
Again, I have no interest in convincing anyone to accept my opinion. I offered an opinion to the original poster, because he asked for opinions. Up to a point, I'm willing to try to clarify that opinion, but I just don't have anything else to add to the discussion...