Axel Jost, located in Germany, has been producing deployants and all types of buckles & clasps for watch straps for over 30 years. I have selected their DF1 model, the finest in their line (and plan to add more in time). They make and supply deployants to several top tier watch companies, of course too secretive to share, but they did confide in me as part of my qualification process.
Skilled German craftsmanship, solid assembled parts, modestly priced for this level of quality.
Add a brushed finish to any deployant for $3, click on link at the bottom of this list