You are correct in that there were "garbage" watches built back then as there are today. One starting place to get an education is to do a google search for railroad watches and bullseye watches. Railroad watches were quality timepieces in the time before computers, radios, and telecommunications. The railroads relied entirely upon well calibrated timepieces in order to safely operate. Train conductors absolutely had to keep to a fixed schedule or you ended up with telegrams trying to occupy the same space at the same time with disastrous results. Now alot of your bullseye timepieces were the Everyman watch and didn't have to meet the same high standard. Some were quite functions and others were not. Do your reading and it will fascinate you. Another point to follow up on as suggested if you choose a mechanical you will news to find a qualified watch smith which can be a very rate bird these days.
If you opt for vintage be Watergate some of the older ones requires a separate key to wind it.