As something of a biscuit connoisseur, I used my colleagues for a taste test of my staple favourites recently - the mighty Bourbon.
I selected Tesco value, Tesco own brand, McVities tasties and Sainsbury's own brand and did a blind taste test. Asda Bourbons were not selected since they have violated the sacred standard Bourbon form factor and gone for a sort of short squat aspect ratio which I wholly disapprove of, as well as God knows what differences to the recipe.
Interestingly, the 'premium' McVities ones (at >4x the price of Tesco value, adjusted for pack size!) come third in aggregate score, with the Tesco value ones coming top. But it was very close and all agreed that their ratings were almost arbitrary and there was virtually no difference that they could discern, either visually or gustatorily.