Michael Bowen suggested this would make an interesting subject(in a comment on the post "The power of Kimi") and I agree. It will be interesting to see who comes out on top. To make it worthwhile, let's have at least one reason behind your choice. There are two categories - current Formula One drivers, and drivers from the past. (You never know we may even get some statistical analysis from IDR at the end if enough of you have a go). Of course in Europe, America or South America, it is unlikely to be a pint...
To get the ball rolling here are my choices:
Current drivers
My choice would be Kimi. When I met him in Barcelona during pre-season testing, I was amazed by his general easy-going warmth and humour. The guy may not be the biggest intellectual on the grid but you can tell he would be a laugh and a half to have a drink with(and I would imagine one pint would certainly not be enough).
Driver from the past
There will only ever be one James Hunt. My wife adored him so did millions of Britons. A vulnerable individual in many ways from what I can tell but with a wild and rebellious streak. A night in the pub with him would certainly have been character-forming. (Interesting that Kimi chose to call himself "James Hunt" when entering that skiddoo race in the pre-season last year).
Pic of James Hunt by Michael P. Whelan via flickr