For what it's worth, I think Nadal and Federer are both great players.
But I also think Nadal is a complete cnut, who, when watching, continually breaks little rules but yet still gets away with it. He has a tantrum when he loses, and always seem to develop a knee issue when he is losing or looks tired.
A friend is a co owner of a tennis school, and federer visited a couple of years ago. He spent close to 3 hours there when he was only supposed to stay 1, so that every kid there could knock with him. He's a good guy.
So I'm not really a fanboy, but I have reason to dislike one, and like the other.