Re: Who Is Greater - Nadal or Djokovic?
It's an interesting one. Novak plays better for longer periods. He has more weeks at #1 and is the only guy to get remotely close to Federer's Grand Slam finals streaks. He had a ridiculous 2011 when he blew away Nadal, and had the upper hand against a still very good Federer. Since then, he's been good but not great, except for once-in-a-blue-moon matches where he just blows opponents off the court (see early 2016). He also has (had?) a tendency to peak for the biggest matches.
Nadal has only ever consistently dominated on clay, but in 2010 and 2013, he showed that his peak eclipsed Novak's average level of play. His Grand Slam numbers are inflated somewhat by his clay dominance (during the period when Federer was far and away the second best on the surface) and his superior physicality over five sets.
Overall, Novak clearly has the edge thanks to his consistency. I'd love to see 2013 Rafa up against 2011 Novak, but I have a suspicion Novak would take that too.