PROS: Acrylic is a water-based, cost-effective solution for metal roofs. They can be tinted easily and are not extremely slippery when damp which makes it an excellent choice for steep slope metal roofs.
CONS: Erodes with weathering and do not perform well in ponding water situations.
PROS: Polyurethanes have better tensile strength and impact resistance with good resistance to ponding water. This makes it suitable for sealing fasteners, flashings and waterproofing gutters.
CONS: Pricey compared to other coatings.
PROS: Silicones have better weatherability than other coatings with little to no erosion. It performs well in ponding water but this is usually not a problem with metal roofs.
CONS: Silicones are softer coatings and do not have the impact resistance of polyurethanes. It also holds dirt and is usually not recommended for surfaces that are visible from the street. Re-coats can only be made with silicone.