Tie: Colt Mk IV Series 70 Government Model Jammamatic. Wouldn't get through a full magazine of hardball without a jam. Tried different ammo, different mags, to no avail. Went back to Colt's repeatedly for "warranty" work, remained a jammamatic. Vowed NEVER to get another pistol with the pony on it, largely due to Colt's NON-service.
Kahr P9. Lots of problems. Failure to go into battery. Failure of slide to lock back. PREMATURE slide lock. Trigger pin walked out. Trigger failed to engage the striker. After the 3rd trip to the factory, Kahr replaced the pistol Traded the new - unfired! - replacement for a G26, which has the virtue of actually WORKING. (To Kahr's credit, unlike Colt's - they TRIED to make things right, and paid for shipping each time it went back.)
Surprised to see someone else pan the BHP . . . my Mk III works exceptionally well, even with cheap ProMags. (I carry it with "real" Browning magazines.)