"Best" is a pretty broad statement. Best for what? Most durable, fastest, strongest, best color, least stretch? Not every material is best for all areas. For instance, ultracam has the least stretch and 8125 is generally considered the fastest.

That said, the material is less important than the technique used to tie the string and serve it. The number of strands used, will allow greatly affect the string's shooting characteristics. My opinion is that it's important to get a good string builder to make your strings, using the same materials each time. This way, you will know what to expect in regards to creep, shooting characteristics and durability.