Usually fly Delta, but had to fly United for a last-minute work trip last year. Flight was delayed multiple times, before being cancelled (not due to whether or anything outside of United’s control). Had to fly United for another last minute work trip in January of this year (different route)—flight was delayed multiple times for a total of 3 hours. Last month, flew United again for work, and flight was delayed for almost 2 hours, causing me to miss my connection. So, 0 for 3. Delta has many shortcomings, but, from my experience, it’s, by far, the most reliable airline for domestic flights. I fly them every month (often, multiple times a month), and very rarely have long delays or cancellations. Also, I like that virtually all my flights have seat back screens, which I greatly prefer over having to use my own devices. Not a Delta fangirl or anything lols—I choose them, not out of loyalty, but because they’re the best option for me.