There are a few reasons why firstly when the animals were fighting the humans snowball was the one who saved them all and he was determined to stop them taking over with a injured back. This shows the idea of equality and determination. Also he was not corrupt and would not have eaten the animals food. Also the windmill would have been done quicker as snowballs determination would come into play. However after the windmill would have been completed there may be more work for Snowball as he would not go to any other farm to trade so they would have had to harvest the stuff or steal it which I don’t believe Snowball would do.
Also Snowball's intelligence and concern for educating the other animals would have provided a longer-lived and better producing farm. He would have constructed the windmill personally unlike napoleon, and it would have provided greater use for both the comfort of the animals and for farm production. The animals would have been better provided for. Snowball would probably not have done the extreme things that Napoleon did such as the guard