This thread keeps popping up. I'll bump it. And in so doing, I note it started last summer prior to the grande boucle.
I'm going to assume this is asking best pro active now and put a spin on it of "who would you be most afraid to face in a [pull a profile out of a hat] race." Rather than who has the biggest palmares so far.
I'll +1 Vos. And give WVA a lot more attention that he seems to have gotten in this thread so far. Extraordinary showing winning in the mountains, against the clock, and on the Champs. Plus in the classics and crushing the CX circuit this year. Talk about an all-rounder.
If we want to stick with "who brings the most to the road" in the OP and not "the [sport]" then we can discount what happened in the mud, sand, and snow. That closes the gap a bit but I still think, despite Loulou's rainbow repeat, the honor goes to Wout because of the diversity of his wins.