There are a lot of physiological commonalities but we are all different as well. E.G., some people have more fast twitch muscles, some slow twitch. Some have enormous aerobic capacity, others not. Alberto Contador stands and flings his bike all over the place while Vincenzo Nibali stays seated and hunkered over with his hands on the tops or hoods. Jan Ulrich did a slow mash up mountains while Lance did a fast spin. Who knows who is actually better - naturally.
A Sports Physiologist will tell you that you can generate the most power leaning forward on a drop-bar road bike and pulling back on the handlbars (tops, drops, hoods doesn't matter). Interestingly, next most powerful is sitting bolt upright on a city bike with no weight on the handlbars. And third is leaning partially forward with some weight on the flat handlebars.