A mild 7.
Roglic was probably stronger in the Tour, but he didn't face a Pogacar. He was dropped on several MTFs, but still won thanks to his team, his ITT and the bonifications. He actually won it in those uphill sprints for boni seconds, although you can't know for sure that the race would have gone the same way without those. 2020 was clearly the year of Roglic, but his Vuelta win in itself wasn't that impressive. Sepp Kuss was stronger than his leader on the Angliru.
Carapaz was the strongest climber overall and had attacking spirit, but he didn't get enough support from Ineos. Movistar was strong as a team, but Mas lacked that bit of extra on the crucial moments, and had a disappointing time trial. Hugh Carthy is the revelation of the race, although he has an ugly climbing style. It was good to see Dan Martin back at his old level. Wout Poels could probably have podiumed in a GT if he hadn't wasted his best years as a helper. Disappointments were Pinot and Dumoulin. Chaves started well, but then it went wrong again. Tim Wellens deserves a mention with two tactically brilliant stage wins.
The course was fine, with the focus on the Angliru and the time trial, but some other stages turned out to be a bit tougher than expected too. Of course the sprinters didn't get that many chances, mostly because the Dutch stages were cancelled. All in all I think this was a fine Vuelta, but a bit too predictable and without a massive performance or anything to be labeled "legendary".