Alcaraz - We can argue the level of someone who gets into three five-setters, but those were all great matches, and to win all three of them, against a former champion and far more experienced player, a probably much better hardcourt player, at least in theory at the time, and then an overwhelming home favourite, was some serious ship. Coming off the back of them and beating a top 10 (heh) player with as much relative ease as he did was incredible. This has been done one other time in history that I know of, and is not to be sneezed at. First round with Baez was also fantastic while it lasted. A real war. The way he comprehensively outdueled Brooksby was great too. This was an absolute blast of a two weeks of tennis. One of my fave slam runs in years.
Medvedev - He got into a real tussle with Botic for two sets there, but it was impressive how he came through it (unlike Thiem in his final). Other than that he was basically untouchable. The final was immense.
Sinner - He started his first two matches so poorly, and then finished them so well. Something similar happened against Paul. He really stepped up when he needed to against Medvedev. The semifinal was an impressively mature scrap in tough conditions where he never really looked troubled, and the way he took control of the final in the second half of all three sets was Top Guy-type stuff.
Djokovic - I'm putting him here because as far as I can remember I only watched the last two matches (I must have watched Fritz and Djere, but I cannot remember a thing about them...). He was very impressive in them, for sure, but compared to the rest of these guys he's so much further along, better, more experienced and thus held to a higher standard that more is expected of him.
Thiem - For 6 rounds he really was brilliant. I remember how HYPED that semifinal was, and he won it with EASE. The final really was an all-time piece of crap though, and significantly detracts from the overall thing.