Marcus of Bond St

I travel to Marcus at 170 Bond Street, home of THE MOST IMPORTANT COLLECTION OF WATCHES IN THE WORLD, and peruse the goods on display. Rather to my surprise, the only "brands" I recognise are Audemars Piguet and Piaget. I notice that there is precious little to choose between the watches in terms of time, though obviously some are running faster (or slower) than others. So clearly prospective customers make their choice on the basis of some other criterion. But what criterion? Closer examination reveals that the timepieces differ widely, and indeed wildly, in price, so perhaps cost is the key. After due reflection, I decline to make a purchase.