I sort by headstamp. Most of my boxes of reloads use different charges for test purposes, so even brass from the same batch and box, reloaded the same number of times, will not wear identically.
I have a piece of .45ACP brass marked "Peters" (not Remingon-Peters). No clue how many times that it's been fired, but if it is really from the Peters company only, it has to be pretty well used. It's in great condition!