There are a few things to consider here.
1st, the #1 cause of death from electric shocks is ventricular fibrilation, around 100mA or so (Depending on several factors) of 60hZ AC will cause the heart to go into fibrilation, to survive usually the victim will need, drum roll.... a DE-fibrilator, which uses DC to stop the heart, after the heart has stopped CPR is more effective and many times the heart starts beating normally again. This makes SC more dangerous.
2nd- AC has a skin effect, meaning the center of the conductor is not used, think of the curretnt flow cross section looking like a donut. DC uses the entire cross section of the conductor, now when that conductor is an arm or a leg the center of the "conductor" is bone (Poor conductor) which increases the effective resistance of the limb for DC compared to AC that flows around the bone and through the circulatory system and nervous systems, both of which are excellent conductors. Another reason AC is more dangerous.
3rd - the biggest factor in determining how much damage is done by a current flow is duration. For AC it takes about 10-20mA to cause a loss of muscle control, and AC causes the muscles to contract (Hence the time honored practice of using the back of your hand), so with AC, at around 15mA or so you can become stuck on the circuit and then duration increases, many times you will be stuck until someone kills the power. DC is very different, it takes around 75mA of DC to cause a loss of muscle control, and it causes your muscles to stiffen, rather than contract like AC does, so it is very hard to get hung up on a DC circuit. The 3rd and last reason AC is more dangerous than DC.
However, speaking from experience, DC hurts more.
