it's hard to say. they developed games suited to the conditions. i've seen nadal exhibit great touch at times, but it's not the cornerstone of his game, obviously. of the three federer's game is the best showcase for 'talent' in the broader sense, and i think it's a given that he'd be at or near the top in pretty much any era.
i would put edberg very close to roger in the talent category. i've read articles where he said that he simply loved to attack, attack, attack and cultivated his game accordingly (hence the conti forehand, simply a means to get to the net, really). but if you watched his career it was obvious that had he cultivated a stronger all-court game, he had the athletic tools to do pretty much anything on a tennis court.