Acrylic is the best material for occlusal surface coverage in prosthodontics because it offers excellent adaptability, ease of repair, and shock absorption. It provides a resilient surface that minimizes occlusal trauma to underlying structures and opposing teeth. Acrylic is also less abrasive compared to porcelain or gold, reducing wear on antagonist teeth. Additionally, it is simpler to adjust and modify chairside, making it ideal for occlusal surfaces where frequent adjustments are needed. These properties make acrylic the preferred choice in functional occlusal coverage in prosthodontic appliances.

Reference: Contemporary Fixed Prosthodontics, Rosenstiel NF, Land MF, Fujimoto J, 5th Edition.