It depends really. Mostly on your leg length and the power your legs supply. Tall skinny people i have noticed are better at doing the longer strides, but i used to be a sprinter for four years in a row and im on the shorter size and more average body with powerful legs and it was a lot more efficient to take short fast strides then long spread out strides. I found when i tried long strides like the coaches sometimes tell you to do, it just messed me up and made me slower. I advise you to run however you feel most comfortable.