Which one is the most important for increasing the sales volume?

First Of All company Brand Value.Brand Value is the most important for sale increassing.And the quality also.As an example Xiomi phone quality is more better than any other Brands .For there better quality they are known as Brand also.

Oh dear.  The most important thing is missing from the list.

Value.

There are too many factors that can influence the answer for a given company, in a given market or in a given economy. A specific marketing focus may be the key to financial stability and steadily increasing profits.

The brand is the most important factor for increasing sales volume