Maybe we should look at stand-out performances, against other velo d’or competitors. Mvdp has those performances in MSR and worlds. Pogacar in RVV. Vingegaard in the Tour. Remco in LBL. WvA in collecting 2nd places. 
So at the moment, I have mvdp, Vingegaard and pogacar as top 3, but it’s still hard to rank them, especially as the season isn’t over. If mvdp wins mtb worlds, he is always in pole position to win for me, as he then has won cx, road and mtb worlds,  but in that case Vingegaard should not win the Vuelta with panache.