power-wise, there is not much difference. They can be just as good climbing hills as each other. However, with crank drive, you have to select the right gear. When you do, you get about 10% more torque for the same input power. Vice versa, if you are in the wrong gear, you will lose not just 10% power but also run the risk of damaging your motor. It's like climbing a hill in your car in fifth year instead of third gear.Ok, why would a crank driven one make much difference, are all hub powered ones not very good then?
The stress and strain on a crank drive is inversely proportional to your cadence. If you have the habit on spinning fast, then it's good. If your cadence drops to under 30 rpm, half of your battery power is converted to heat, not good for the motor. So on a CD bike, you need to keep your cadence to 60+ all the time.