Better and Best quality

Better adjective - (comparative of `good') superior to another (of the same class or set or kind) in excellence or quality or desirability or suitability; more highly skilled than another.

Best quality and better are semantically related. In some cases you can use "Best quality" instead an adjective "Better".

Better and best quality are semantically related. Sometimes you can use "Better" instead an adjective phrase "Best quality".