Switzerland with little white gloves, anal employees with tons of experience and centuries of passed down knowledge
If you ever go to Biel you will be supprised how many migrant people there are wandering round that town. Switzerland has to import watchsmith from all over just to fill the demand admitedly only the best get to work for the big names but i do not think that the ETA factory is full of old swiss gentlmen tinkering away i belive the answer is like any large industry.
The chinese are getting close to the quality that we get from switzerland it is just the QC that we get in reps where the failing comes to play.
Buy official marketed asain 2824/ ST16/ST18 and i have been impressed with what i got, particualy when it costs 1/4 of the price
Oh and ETA used to make movements in China ect, so there are a ot of ETA trained watchsmiths over there as well.