I, too, have had liner locks, lock backs, axis locks and frame locks and have never had a failure. I'm not crazy about either the axis lock or the liner lock. The axis locks have springs that can and do fail. At the wrong time, a failure could be very painful. My experience with liner locks has been with several CRKT knives, a Buck Strider (not a cheap knife) and a ZT 0200. The the only one of these that looked as if it were really sturdy and nearly fail-proof is the ZT 0200. I have several Spyderco lockbacks and I love these, even though the knives don't operate as smoothly as the liner locks. The only frame lock I have is a large Benchmade Skirmish and the blade is so large that I can't snap it out with my finger unless I use some wrist snap with it. It at least appears to be the stoutest lock of all. So, the short answer is that I prefer the lock backs to the liner locks.