I think there's an argument he's the best actual defender on the planet.
He's not as complete an all-round CB as Van Dijk - his passing isn't as strong and he lacks the blistering pace - but as an actual defender I don't think there's anyone better. De Ligt has been incredible at that kind of stuff for a while at Juventus and Chiellini was exceptional before his injury but that was 15 months ago and he's not come back properly.
Other than those I don't think anyone is even close. Sule at Bayern had a spell when he had that inpenetrable wall aura, but he fell off. Gimenez at Atletico used to but his injuries have tarnished it a bit.
He's just the best at defending. Marking, tackling, blocking, organising, no body is better.