I think they would be very even, even though I gave my vote to Fed. When Federer was at his peak, Djokovic was still not fully matured, and it seemed Djokovic would never be able to beat Fed or even Rafa who is just 1 year older. When Fed got old and declined - from when would be hard to decide, but people already ruled him out of slams in 2012, so, I think 2012 Federer was already seen by many as declined and old - he just couldn't beat Djokovic at slam level, BO5s. I guess 2010-2012 would be good years to look at when it comes to Fed v Djok rivalry, and to me, it seems quite even. Federer having the upper hand in H2H in 2013 is huge, as that was one of Djokovic's peak years and Fed was quite far removed from his peak, but Fed still couldn't beat him in slams, showing for older players, it just becomes harder to maintain focus and the level of play over 5 sets. This might give Djokovic's younger rivals of today, Sinner and Alcaraz, a bit of an advantage in the future clashes, but Alcaraz is still young at 20 and still improving, so let's see.