Do you swap cases, boxes, bentwoods?
If you collect, you probably don't keep everything in tables. I know that all things being equal, given the choice, I prefer a case with a cover to a tabled machine.
Say you have 3-4 Singer 201's. You plan to keep one. One is in a Bentwood case, one in a covered box case, ones in a treadle cabinet, ones just a head. The head is the best of the four and the one you'd like to keep. What do you do?