I voted for Ayuso, Mas and Vlasov.
Given his exploits at such a young age it would seem likely that barring injury, Ayuso will win at least a Vuelta one day.
Mas could still win a Vuelta. Though I think it might be a good idea to also give the Giro a go (when there are low ITT kms).
Vlasov....has developed a winners confidence. Only in one week races, but I think it more likely he transfer that to three weeks, then a 4-10th level guy like Gaudu becoming a GT winner.
As for the others; Arensman....almost as likely for Sivakov to have a magical winter and be as much in the GC GT picture. Landa and MAL still pretty good, but probably missed their chances. Rodriguez a solid chance, but you can't say yes to too many with all of the current GT winners to fight against.
Nobody has mentioned Pidcock anywhere here. Will be interesting to see if he can improve his climbing further.