Roglic is at this stage of his career a tough-to-beat elder statesman, who's ceiling is not as high as the very best in business, but who has no real weakness as long as he stays healthy and is usually very consistent.
The only one in this Vuelta startlist who could outclass him is Vingegaard, but he has a gruelling Tour in his legs and I would be very surprised if he can reach a level anywhere near to that shown in July. Nothing he did at the Tour indicated he was leaving something in reserve for the Vuelta. Also doing back-to-back GT-s is a new expierence for Vingegaard and it's very doubtful either himself or his team can be as certain about his numbers and form curve as they were during the Tour. Because of this I for now favour Roglic over him .
Remco is also very consistent, but could just lack the top end climbing ability needed to beat the Jumbo duo. Flat TT should give him an advantage, but the TTT on the other hand likely favours Jumbo guys. There is still some uncertainty surrounding the real reach of his abilities in a 3 week race, due to how the ones he has done have panned out so far, but for me he is a slight underdog going in.
Ayuso is a wild-card and the likes Mas and Thomas cannot be counted out. Specially the latter can be very dangerous, but somehow always flies under the radar in previews like this.