According to user experiences, the worst airlines include Philippine Airlines, Delta, American Airlines, United Airlines, Ryanair, and Spirit Airlines. These airlines have been criticized for issues such as cramped seats, poor service, bad food, delays, and lost luggage.

Philippine Airlines is considered one of the worst airlines due to extremely packed flights with tiny seats and a particularly unpleasant layover experience in Manila. Passengers have reported long queues and crowded conditions.

Delta is considered one of the worst airlines by some users because of their overall negative experiences, which have led to strong sentiments like 'life is a nightmare' when flying with them.

American Airlines receives poor ratings from users due to a general sense of dissatisfaction and frustration, summed up as 'because fuck you that's why,' indicating a lack of customer care and poor service.

Common complaints about United Airlines include a severe negative impact on mental well-being and a frustrating user experience on their website, making it difficult to navigate or click off their site.

Ryanair is often criticized for being the 'least dignified way to travel in Europe.' Passengers encounter a cumbersome booking process filled with upsells, long commutes to secondary airports, and uncomfortable seating made from cheap plastic.

Passengers face issues with Spirit Airlines that liken the experience to 'the greyhound bus of the sky,' indicating a very basic, no-frills service that leaves much to be desired in terms of comfort and overall experience.