Let's just get this clear- this is speaking from my own experiences. I obviously can't speak for anybody else. Here's an M6.
I think that United Airlines should win the award for "Most Delayed or Cancelled Flights for No Good Reason." In the past three times I have flown with them, they have delayed or cancelled five flights that have really screwed up my plans. First, they delayed a flight because of a broken air conditioner when it wasn't even 75 degrees. That caused me to miss my connection, forcing me to fly into a different airport and drive four hours at 12:00 AM. On the way back, they delayed the first flight, then cancelled my connection flight, causing us to be rerouted to an airport three hours from home (instead of 20 minutes). My dad had to drive out and pick me up (at 12:00 again). Yesterday they delayed the first flight, which would have caused us to miss the connection. Strangely enough, there was no inclement weather at the destination or the departure area, nor was there any in between. We decided it would be best to fly straight to a different airport and take a different connecting flight to the destination. The connection got cancelled. We decided to drive three hours to the destination. Luckily we are flying Southwest back.
TL;DR- United Airlines delays a lot of flights. I also suddenly realized I sound like a whiny bitch. Oh well.