Can't go for Lewis as he has made too many mistakes in the races this year. Couldn't vote for a Ferrari driver as they are cheats who break the rules and the spirit of the rules, can't vote for either Red Bull driver as both have made far too many mistakes and Vettel only won it in the end due to the support of the team to the detriment of his team mate.
Nearly went for Rosberg as he has had a fairly good season against a team mate who is a 7 time WDC, but then his team mate has been out of the sport for 3 years, so will reserve judgement until next year on that.
No-one further down the grid really springs to mind, can't see the fascination with Kubica personally and won't be able to until he gets a decent team mate (and knowing what Renault used to do to their second Chassis when under control of the one who shall not be named, it wouldn't surpise me if they carried on that 'tradition').
Can't vote for Kobi as he just hasn't been that good this year. He is interestingto watch, but he was dire earlier in the year and got beaten by Heidfeld at Abu-Dhabi (who showed one again why he got his nickname, but Kobi should have been faster as he is much more used to the car).
So, I have gone for my default of Button. Ok, so his qualifying let him down, Other than that though, the only bad call he made was in Korea when he decided to keep the new brake system on the McLaren and kept locking the front. The only DNFs he had were one mechanic having brain fade at Monaco and Vettel doing his usual 'lets take another driver out while attempting an overtake', neither of which were his fault. He has also lived up to expectation (for me and other JB fans) of staying with his more illustrious team mate and even beating him in the early part of the season. On race pace, he has always been there or there abouts.
So, although i'll get moaned at by FB, Muddy and Bro (to name a few), Button is my choice for driver of the season.