I can only recommend these.
I currently have these on all my guitars and basses, and the work wonders. I've never had any of these fail, and the sturdy materials just seem to never fail.
I prefer this system, where you look the strap down into the Strap-knob, over the regular system where you set the strap on the knob with a hook-like system.
Would recommend these, or similar strap locks over any other strap lock on the market right now.