Thomas Cook Airlines has been named as the worst short-haul carrier by a consumer watchdog.
The company had the poorest results for overall customer satisfaction and the likelihood of being recommended to a friend.
A panel of more than 8,000 Which? members gave the airline a rating of 37%, while Ryanair was scored at just 38%.
The cabin environment of Thomas Cook Airlines was given one star out of five and Ryanair got the same rating for the quality of its boarding process. Both airlines were given two stars for their value for money.
Swiss International Air Lines was voted as the best short-haul carrier with a satisfaction rating of 76%. Aer Lingus came second with 67%.
In the long-haul category, Singapore Airlines came number one with a rating of 89%. Air New Zealand was second (88%) and Emirates third (80%).
Rochelle Turner, head of research at Which? Travel, said: "The airline you choose can have a big impact on your trip, making the difference between arriving feeling tired or refreshed.
"The top-rated airlines all score highly for both the cost and value for money of the flight and most still include free hold luggage, plus onboard drinks and snacks in the ticket price - something clearly prized by travellers."
The survey questioned 8,277 Which? members about their most recent return flight. Some 2,179 had travelled long haul, and 6,048 short haul.