Fed was the most talented. I think this is pretty clear. However, he clearly struggled mentally, whether that be clutchness or being too stubborn in his playstyle. While he may have been a hard worker and trained a lot, he clearly never had the intensity or love to train like Rafa did. I mean, when you are that talented, you simply dont need to.
Djoker was mentally the toughest. The number of clutch moments he has had. Plus, the IQ he plays with is pretty condoning to winning. He overcomes quite a bit mentally. Without his mental toughness, there is a good chance he has about 10 slams.
Rafa clearly worked the hardest. The way he trained and how much he trained was enormous. The intensity he plays with shows this as well. That said, it probably also cost him in the long run due to his body not being able to stay healthy throughout his career.
Yet, Rafa seems to be second in talent, not far from Fed. Rafa seems to also be second in mental toughness, not far from Djoker. Rafa seems to have encompassed all three aspects at the highest level or right below the highest level possible.
Or, and I might be crazy here, but maybe Djoker is way more talented than we all give him credit for?