Chose the company and and flavour you like and for the reasons says how everyone would buy it, why you like and how you know a lot of people like that flavour, you can say that this flavour is really rare to find it and how when you buy this flavour from another company the chips finishes imidiatly. Say how everyone buys that flouver from the other company and never is left enough for other people to buy it. I hope this is helpful to write your essay