He is clearly better than Hansen. Physically, perhaps only Koulibally compares with him, but Van Dijk is faster and more nimble.
Its a very big statement to make. If you are just comparing defensive attributes, VVD has the potential to be the greatest in the world. But he is not better than Alan Hansen, not yet.
There are times I feel being too good puts him into a false sense of lull and he gets sloppy. In that game against Bayern, despite his goal, he was not great. He left too many balls run behind him and of course he did recover with one turn and giant stride nicking it out to safety. But too sloppy by his own golden standards. I have seen something similar in many games recently, where he has allowed the ball (not the player) run behind him and then used his stride to nudge it to safety. I would prefer he runs back and not risk, but he is that confident that he just turns around calmly and confidently nudges it. Hope it doesn't cost us in the near future.
But again I am nitpicking on minor things here and there. Overall he is been absolute Colossus for us, best CB in the world right now. He is better than Sami Hyppia and thats saying something. Two more years of consistent defending, VVD will be right up there with Hansen and the others.
Also don't think Koulibally, as good as he is, compares with VVD. VVD is better. Only a young Chiellini may be (but then he rolls on the ground like someone shot his balls every time wind blows)