If you mean actually used in combat, then many already listed are out of the running, IMO, as they haven't seen combat use. A stock BHP is pretty good, used by many forces for years. The CZ 75 and it's scores of clones are OK. The Beretta M9 is certainly considered an accurate pistol The HK P7 was used by several forces,
GSG9, ROKs, Greeks. But the HK MK23 is a match ...