I've operated both Lycoming and Continental, and I've found both to be good, solid engines.
Currently, I operate a Lycoming IO-540 (300 HP) in my private aircraft (Cherokee Six). I fly night IFR over mountains...and most people think I'm an idiot (for that reason and possibly for others, as well...
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But, I believe that engine failures are due, primarily, to poor maintenance and improper operation. If you maintain the engine properly, do regular checks (including oil analysys, etc.), operate the engine as per manufacturers' recommendations, give it fuel and oil, etc....it usually won't quit. You have much higher probabilities of crashing for reasons other than engine failure.
In fact, I've never had an engine failure on a piston airplane. Had a rough-running Continental one time, but eased the aircraft to the nearest airport, made a safe landing, had the repairs made, and off I went never to have any further problems.
In most cases, engine failures are due to no fuel, contaminated fuel, no oil, intake icing, a destroyed and ingested air filter (due to poor maintenance), etc. Seldom does a well-maintained and properly operated engine just up and quit. And in the very few cases where it does, it was telling you for some time that it wasn't feeling well, and you simply weren't listening.
PantLoad