+1 for Dunlop's Dual Design StraplokThe Dunlop ones have never let me down. They are on all my important guitars.
http://www.musiciansfriend.com/strap-locks/dunlop-dual-design-straplok-system
+1 but Don't buy the Schaller style knockoffs on ebay as they are harder to put on and take off!Schaller. Never let me down.