Doggy is one position where I can actually last longer, although when I cum while fucking in this position, it is usually more intense!
The position that brings me to orgasm the quickest is missionary, and unfortunately it has been the favorite position for most of the women I've been with. Given a choice, I like to start with doggy or cowgirl, and finish with missionary. If I'm lucky enough to go through all 3 positions, I have been able to last 15-20 minutes of pure fucking and my orgasms have been epic!