Well AO title says it all how good Djokovic is on hard surface and that is the main thing why i think that Djokovic is better on hard court. On grass court there is no doubt honestly. Medvedev also lost today against Bautista and with such bad results Medvedev is ranked #1 and i think he dosent deserve it
AO title says one thing, but US open title says other thing
at the moment, it is hard to say who is better on hard surface, Djokovic is not comparable with Medvedev when career is in question, but at this particular moment, their odds (if Djokovic will be allowed to play) on US open would probably be pretty close
but on grass, there is no question, and not just for Djokovic, even if he plays, Medvedev would not be at top5 favorites for the title, you can just look at outright odds for Wimbledon, and compare it to both, Singles list ATP, and Singles race, and it is totally different
because grass is different