CNC cylindrical grinding machines are specialized machines that are used to grind the exterior surface of cylindrical workpieces. They are commonly used in the manufacturing of heavy equipment, aerospace components, and other industrial applications that require precise and accurate cylindrical grinding. The best-selling CNC cylindrical grinding machines can vary depending on the specific application, industry, and region. However, some popular and widely used models include:

1. Studer S33 – Studer is a well-known brand in the CNC cylindrical grinding machine industry and their S33 model is known for its high precision, efficiency, and versatility. It offers a wide range of grinding options for different applications and industries.
2. Kellenberger Kel-Varia – Kellenberger is another well-known brand in the CNC cylindrical grinding machine industry and their Kel-Varia model is known for its high precision and reliability. It offers a wide range of grinding options for different applications and industries.
3. Toyoda GP-100 – Toyoda is a well-known brand in the CNC cylindrical grinding machine industry and their GP-100 model is known for its high precision and durability. It offers a wide range of grinding options for different applications and industries.
4. Junker Jumat – Junker is a well-known brand in the CNC cylindrical grinding machine industry and their Jumat model is known for its high precision and productivity. It offers a wide range of grinding options for different applications and industries.
5. Schaudt Mikrosa – Schaudt Mikrosa is a well-known brand in the CNC cylindrical grinding machine industry and their machines are known for their high precision and efficiency. They offer a wide range of models for different applications and industries.

It’s worth noting that the best-selling CNC cylindrical grinding machines also depend on the region, some brands might be more popular in one region than another.