What should be the best value of diversity factor ?

diversity factor is the ration of the sum of individual max demand of customers to the max demand of the system.

it is always equal to or greater than one.

it depends upon the number of customers to be served hence no best value;

typical values could be taken as : 

1.0 for1 customer

1.5 for5 customers

1.6 for10 customers

1.7 for30 customers etc.