Some time ago, I purchased few types of straplocks for my leather strap. After testing all of them, I decided to stick with those made by Gotoh.
Great overall quality of production, mechanism works smoothly.
There is just one problem. Bolt nuts, which keep straplocks attached to the strap, may get loose over-time. In this case, I would suggest to get additional pair of these nuts (M12x0.5mm). It should solve problem for good.