Even if all you care about is "big wins" and choose to ignore everything else he still has a lot of them
He has nothing comparable to Sagan
OK, Van aert has Strade, and Sagan has Roubaix, which is a bigger win
Sagan has won 3 GW and Van Aert only 1. Sagan better
Ok, Van Aert won Amstel, and Sagan won Ronde van Vlaanderen, which is bigger. And when Sagan won De Ronde, it was actually clear to see that he crossed the line first (he drop Cancellara like a stone in the Paterberg)
Sagan has more TDF stage wins
green jersey aren't exactly insignificant wins
Yes , Green Jersey is quite a significant win for a rider. Which is why Sagan 7 green jerseys put him in a different league to Van aert 1
Fair enough, this is Van aert biggest win and it was very good. But it does not compare to 3 consecutive World championships Road race wins. A historic and unique achievement.
He lost RVV against MVDP by a few centimeters for example
So you named 5 races, only 1 of which is at the top echelon of the sport (monument/World championships/ Grand tour GC) , and you already talking about races Van Aert lost.
By the way Van der Poel rode a poor final in that 2020 RVV. He led onto the paterberg, drove the pace consistently and led out the sprint, despite having a teammate behind when Van aert didn't. He gave Van aert an armchair ride to the finish and Van aert still lost.
You could mention how sagan barely lost 2013 Sanremo to ciolek, or sagan barely lost 2016 Sanremo when he was in prime position and crashed by gaviria mistake. Sagan gifted 2013 strade bianche to his teammate Moser. Sagan was catching Gilbert for 2017 ronde van Vlaanderen when a spectator left their clothes over the barrier.
So sagan has a lot of what ifs also. Winning matter the most
Based on palmares at this point he isn't a better rider than Sagan (yet) but I would say he is on track to doing so
OK. So let's go to arnau de lie/olaf kooij/magnus Sheffield threads. And discuss whether they are better than Sagan, because in 12 years they could be on track for doing so.
You admit that Sagan is better than Van aert yourself, but if the future goes as you hope Van aert might be comparable to him. Anything can happen in the future. Sagan could win something big this year.
We can talk also about Sagan wins in Giro and vuelta. Sagan Giro points jersey. Sagan wins at tirreno, Paris Nice. Sagan wins in quebec and Montreal. Sagan win California GC, sagan wins at Suisse, Sagan European championships etc