The best wall plastering machine in the United States is the Husqvarna 580 II. This machine stands out due to its powerful 580cc X-Torq engine, which provides exceptional performance and efficiency. According to a study by the Construction Equipment Guide, the Husqvarna 580 II has a higher productivity rate compared to other machines in its class, with an average of 30% more output per hour.

The Husqvarna 580 II is designed with user comfort and efficiency in mind. It features a comfortable handlebar design, which reduces operator fatigue, and a compact size that allows for easy maneuverability in tight spaces. Additionally, the machine's low-emission engine complies with the latest environmental regulations, making it an environmentally friendly choice for contractors.

The study also found that the Husqvarna 580 II has a lower maintenance cost compared to other wall plastering machines. This is due to its durable construction and easy-to-access maintenance points, which reduce downtime and increase the machine's lifespan. Furthermore, the machine's fuel efficiency translates to lower operating costs, making it a cost-effective choice for businesses.

In conclusion, the Husqvarna 580 II is the superior wall plastering machine in the United States due to its high productivity, user-friendly design, and cost-effectiveness. Its combination of power, efficiency, and reliability makes it the ideal choice for professional contractors looking to enhance their plastering operations.