I'd have a hard time deciding which is my favorite if I had to choose - James May or Jeremy Clarkson. Jezza says all the off-the-wall crazy stuff, but Captain Slow much more of a geek in all kinds of manly areas. I really enjoy his show "James May's Man Lab" as well.
this is why the American version just doesn't work. Top Gear is far more about the three personalities than anything else. It's three ends of a triangle.