Actually as a Fed fan I am no longer sure of this. It was different vis a vis Nadal as H2H was the only thing he had over Fed. Djokovic is not a long way off from Fed's own weeks at no. 1, can get to a sixth year ending No.1. Now on top of this if you add a double NCYGS (as against 0 for Fed), it seems like overvaluing 4 slams. Maybe I can put the mark at 18 instead of 16 but I don't believe Novak has to tie Rog on 20 slams if he gets a second NCYGS. The slam tally as paramount was relevant when nobody went to the moon. Nole has been there once and if he does it a second time that would be just phenomenal. I would be glad too to have lived through an era when a male tennis player achieved it (since it would have been considered utterly impossible in the 90s) and I hope he does.
Federer vs. Djokovic:
Slams: 20-15. Federer leads heavily.
YE#1: 5-5. Tied.
Weeks at #1: 310 - 236 Federer leads by 1.5 years.
Titles: 99-72 Federer. Huge lead.
Masters: 27-32. Lead for Djokovic.
YEC: 6-5. Federer leads.
Win% (Overall, HC, Clay, Grass, Carpet): (82%, 83%, 76%, 87%, 72%) - (83%, 84%, 79%, 83%, 71%)
Intangibles: Federer 3x5, Djokovic NCYGS, Djokovic Golden Masters.
Federer vs. Djokovic (CYGS 2019 + WTF + 5 Masters):
Slams: 20-18. Federer leads.
YE#1: 5-6. Djokovic leads.
Weeks at #1: 310 - 284 (+~26) Little difference, virtual tie.
Titles: 99-81 Federer. Still a huge lead.
Masters: 27-37. Big lead for Djokovic.
YEC: 6-6. Tie.
Win% (Overall, HC, Clay, Grass, Carpet): (82%, 83%, 76%, 87%, 72%) - (85%, 84%, 80%, 84%, 71%)
Intangibles: Federer 3x5, Djokovic NCYGS, Djokovic CYGS, Djokovic Golden Masters.
I suppose it just depends on how much you value the CYGS and Masters lead over 2 Slams and 18 other titles. I don't know how I'd react, but I think I'd be talking it down. If he gets within 1 of Roger, I'll start talking then, but until then I think Federer will stay the GOAT in my head.