I'm pretty sure you'll find at least one thread on every other FT airline forum about maintenance delays with a passenger saying "fly <insert other airline>" next time.
I believe you can get a feel for the state of an airline by taking the temperature of the FT forums. A few years ago, during the depths of the Smisek regime, the UA board was on fire with complaints about operational issues. Today, the forum is pretty quiet and IME United has greatly improved their operations. The AA board was active but not this negative after the merger. It's on fire now. And yes, I'm fully aware that data is not the plural of anecdote.