The original question had to be edited. I think that the argument can be made that Napoleon was more "successful" because he silenced any opposition. What other choice could there be for Napoleon? He was able to use his force of the dogs to kill off anyone who voiced opposition. Snowball's style of leadership was more participatory, more vocal, and one that encouraged the animals to vote and to think about initiatives. Napoleon was more about force. When it becomes clear that the animals are going to side with Snowball about the building of the windmill, Napoleon sends the dogs to run Snowball off the farm. Whenever animals voice discontent, the dogs kill them off.
In this light, Napoleon's leadership style is more "successful" because he does not permit discussion. It is successful because it accomplishes its goal: To enhance Napoleon's power. Napoleon cares about little else other than his own power and his own sense of control. It is here in which his leadership style generates more "success." It is singular in its goal and focus and accomplishes it by any forceful means necessary.