I used to supply very large quantities of watch batteries to Union Carbide in Geneva when I was export manager at Duracell Batteries. They supplied all the top brand Swiss watch makers with UCAR branded cells which we produced in our Duracell factories.
When discussing the specifications with one of their R&D chaps he mentioned that all of the leading watch makers used the three main Far Eastern sources for their surprisingly inexpensive bought-in electronics chips and drive/display circuitry. He also said that even cheap makes and fakes use the same ones since the vast volume produced of the quality ones brought the cost down to a level where it wasn't possible to produce a cheaper 'budget' priced product in the far smaller quantities for the fake watch market.
I guess the 'quality' comes down to the degree of care paid over the finish, the cost of the metal used for the case and strap, plus the retail price which reflects the snob (investment?) value of the very top brands.