How is Snowball a good leader in the book Animal Farm?
Snowball's intelligence, hard work, and competency make him an excellent leader. We learn early on that he is highly intelligent, for he is the best writer among the pigs. Orwell also shows, subtly, that Snowball is willing to work hard in a way Napoleon is not. For example, it is Snowball who climbs the ladder and paints the Commandments on the side of the barn. Snowball also creates Animal Farm's flag and energetically organizes the many animal committees.
Snowball takes the time to educate himself on what he needs to know to be a good military leader. For example, he finds and reads an old book about Julius Caesar's military campaigns. This reading helps him organize an effective defense when Farmer Jones and the humans attack Animal Farm. Without his clever strategy, Animal Farm might have been defeated almost as soon as it began.
While not entirely without some notion of privilege, he is also a true believer in the ideals of the revolution: he is firm with Mollie about no sugar and no ribbons. Animals have to be animals, he insists, not behave like humans.
Snowball studies a farm journal and plans innovations to improve crop yields on the farm. He also makes plans to build a windmill, with the idea of bringing material benefits to the animals.
Napoleon, in contrast, is merely a crass political opportunist who does no work for the common good and has no new ideas. All he is interested in is amassing power for himself and a very few of his cronies. It is easy to imagine that had Snowball's intelligence, ability to plan, and dedication won the day, Animal Farm would have become a much better place.
Snowball genuinely believes in Old Major's message of animal equality and shared sacrifice for shared gain, and so his ideas represent an attempt to create a working communal farm. Although he shares the early luxuries of the pigs, such as the milk and apples which are kept from the other animals, he tries to make things better for them with technological advances like the windmill. His passions are naive, and he is driven out by Napoleon's brutality.
Snowball had made a close study of some back numbers of the Farmer and Stockbreeder which he had found in the farmhouse, and was full of plans for innovations and improvements. He talked learnedly about field drains, silage, and basic slag... Napoleon produced no schemes of his own, but said quietly that Snowball's would come to nothing...
(Orwell, Animal Farm, msxnet.org)
Napoleon's pragmatism proves more powerful than Snowball's intelligence, and the other animals are cowed into accepting Snowballs expulsion because of the threat of the dogs. Had Napoleon been removed instead, it is possible that Snowball could have created the utopian ideal with his drive and his understanding of technology.
The biggest difference between Snowball and Napolean is that Snowball puts his people first. Napolean looked at the situation as a chance to stop working and to get the best (as in food, shelter, etc.). Snowball encouraged the animals to imagine a better future for them and for the rest of the world's animals. He had big dreams that he wasn't afraid to carry out, such as the windmill. Imagination is an important quality in a good leader, which Napolean lacked. Snowball was also not greedy, demanding, or lazy.