Why flyback diode is preferred over fwd body diode of MOSFET in case of H-Bridge?
Wiki says it better than me: -

Body diodes may be utilized as freewheeling diodes for inductive loads in configurations such as H-bridge or half bridge. While these diodes usually have rather high forward voltage drop, they can handle large currents and are sufficient in many applications, reducing part count, and thus, device cost and board space.