The reason I choose to dive into the vintage market is simple: I can afford to buy brand name mechanical movement watches at a fraction of their new counterparts.
It opens on both sides — on the back so you can view the inner springs and gears as they move, and the front so you can tell the time and watch the inner workings.
Some of the most valuable watches are railroad pocket watches because they were produced with government-required exacting standards to ensure they kept accurate time.