There are several Rubber Antioxidants available in the market, but determining which ones are the best can be subjective and dependent on various factors such as the type of rubber being used, the specific application, and the desired performance characteristics. However, some commonly used and highly effective rubber antioxidants include:

1. 6PPD (N-phenyl-1-naphthylamine): 6PPD is one of the most widely used and effective antioxidants for rubber compounds. It provides excellent protection against oxidative degradation, heat aging, and flex cracking. It is commonly used in tire manufacturing and other high-performance rubber applications.

2. TMQ (Polymerized-2,2,4-trimethyl-1,2-dihydroquinoline): TMQ is another popular antioxidant for rubber compounds. It offers good protection against heat aging, oxidation, and flex cracking. TMQ is commonly used in tire sidewalls, conveyor belts, and other rubber products.

3. IPPD (N-isopropyl-N'-phenyl-p-phenylenediamine): IPPD is a versatile antioxidant that provides good protection against heat aging, flex cracking, and oxidative degradation. It is often used in combination with other antioxidants for optimized performance.

4. BHT (Butylated hydroxytoluene): BHT is a synthetic antioxidant that is commonly used in rubber compounds to provide protection against oxidation and heat aging. It is effective at low concentrations and is often used in combination with other antioxidants for enhanced performance.

5. DPPD (N, N'-Diphenyl-p-phenylenediamine): DPPD is a high-performance antioxidant that offers excellent protection against heat aging, flex cracking, and oxidation. It is commonly used in applications where high heat resistance and long-term stability are required.

6. APK (Alkylated Diphenylamine): APK is a general-purpose antioxidant that provides good protection against oxidation and heat aging. It is often used in combination with other antioxidants to achieve optimal performance.

When selecting the best rubber antioxidant for a specific application, it is essential to consider the specific requirements of the rubber compound, such as the operating temperature, exposure to environmental factors, and overall performance expectations. It is also important to consider compatibility with other additives and processing aids used in the formulation.

In conclusion, while there are several rubber antioxidants available in the market, the best one for a particular application will depend on various factors such as the type of rubber, the specific requirements, and the desired performance characteristics. Consultation with a rubber chemist or technical expert is recommended to select the most suitable antioxidant for optimal performance and durability.