Definitely calves.
I have a disadvantage because I have somewhat high insertion for my calves. Although, my vertical jump is very good which lead me to believe I have some fast twitch muscle fibers waiting for me to pound them. Well, I finally have stopped being a wussy and once I feel a burn in the calves I continue for 10 more reps. They may only be half reps but they sure as heck count more then stopping when it gets difficult. It's also tough to do standing calf raises because my gym has no machine for this and I'm too tall to use the the smith machine. I have to resort to holding 100+lb dumbells, which get pretty heavy after 45 seconds.