I've used Schaller, Dunlop and DiMarzio. Currently using Schaller on all my straps. The reasons are: I've never had one fail and I have different straps for different purposes. Like a Mono compfort one for long band practices, a normal Souldier and a Souldier with my wireless pack on.
major reason I don't use Dunlop. I had one fail multiple times with my Les Paul nearly dropping to the ground because it just came out of the strap button. Its only held in by ball bearings,
A little locktite on the Schaller nut and a spanner will sort any loosening problems.