I work in a tool store that sells Makita & Porter Cable sanders. If you are buying a random orbit sander, ask the store to swap out the Hook & Loop (H&L)base for a Pressure Sensitive Adhesive (PSA) base. We don't charge for this if you do it at the time of purchase. It is a reasonable request, though I don't know if the big box home centers (Home Depot, Lowe's) would do it for you. You will save $ on sandpaper.

The one advantage of H&L is that you can change grits at any time without wasting the partially used disk. Both types of bases are available for DeWalt also, and I suspect for Bosch too. I don't know what is available for the cheaper sanders like Black & Decker or Ryobi.