Knowing that car was 0.5-1 second faster than the rest of the field in 75% of races (Hembery stating Red Bulls were 15 kph faster in corners than all other cars in India or Webber saying he drove awful lap in India, yet he started from P2, less than 1 tenth off pole and 2 tenths clear ahead of the rest), I would say a lot of drivers.
One thing is certain. Alonso and Hamilton in such fast car would win WDC in September or at the beginning of October, some 4-5 races before the end of season. Just look at how average Vettel was:
-in Malaysia he collided with Karthikeyan
-in China he had awful qualifying
-in Spain he didn't even try a lap in Q3
-in Spain he didn't slow down for yellow flags and gained penalty
-in Monaco he had awful qualifying
-in Germany he overtook Button off the track and gained penalty
-in Belgium he had awful qualifying
-in Abu Dhabi he collided with Senna, he hit DRS board behind Safety Car, he overtook Grosjean off the circuit and had to do it again
-in Brazil he caused collision with Senna turning into corner like no one was there
And it's not everything, but I don't want to spend more time on mentioning all of his poor sessions or races (like qualifying in Australia, where Webber was faster despite having no KERS, which is worth 4 tenths per lap

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Meanwhile Hamilton was as perfect as you can expect from top F1 driver over one season, with his only bad day on Saturday at Spa. Alonso made few mistakes more (qualifying in Australia, first corner in Japan), but you have to remember his car was 0.5-1 second per lap slower than Red Bull, so it's not great to drive with having that in mind.
Vettel by many 'experts' was described as a new rainmaster and what exactly he has shown in Malaysia in not the dominant car? He was whooping 3 seconds ahead of Webber when he hit Karthikeyan.
Monaco is known as the true test of driver's skills and what Vettel has shown this year in a car, which got his journeyman teammate on pole and top step of a podium? P10 in qualifying and P4 in the race, only because he could drive in clear air, while his teammate was holding everyone up in order to make tyres last till the end (as Monaco was huge tyre saving procession

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And before someone will mention how Webber in all these years couldn't even grab P2 in WDC, which would mean it's the Vettel who is making a difference, let's not forget before 2009 Webber had only 2 podiums. In 2005 Monaco he grabbed 3rd, finishing behind his teammate Heidfeld (who couldn't even find a full-time seat after BMW pulled out in 2009 and was fired firstly by Sauber and then by Renault), while in Europe 2007 he had to defend like crazy his 3rd place against Wurz in a Williams. The same Wurz who didn't even last a season after return to racing, as he had to give his seat to Nakajima in Brazil that year. That's how good Webber really is.