The Dublin-based airline is joined on the list of aviation shame by Heathrow, which was voted the world's least favourite airport in a survey by travel website TripAdvisor.

In a poll of 4,000 travellers around the world, unfriendly staff were cited as the worst part of the Ryanair experience, followed by delays and poor legroom. Low-cost travel fares badly in the study, with easyJet coming second to its Irish rival in a questionnaire of British flyers.

Ryanair has transformed itself from an industry minnow into one of Europe's biggest airlines over two decades. However, its obsessive focus on the bottom line has dented its public image. In one infamous incident, it charged a man with cerebral palsy £18 to use a wheelchair, while in another example of cost-cutting zeal, pilots and cabin crew pay for their own training and uniforms.

Chief executive Michael O'Leary is the industry's most outspoken executive, having advocated the shooting of travel agents and urged passengers concerned about the environmental impact of flying to sell their cars and walk instead.

Ryanair said: "The 42 million passengers who will fly with Ryanair this year have listened to real trip advice and choose Ryanair for the lowest fares and the best punctuality."

Ryanair's most recent outburst against the aviation establishment came this week, when the airline lashed out at the owner of Stansted airport, its UK base. The company urged thousands of passengers who suffered delays in the half-term rush to send all complaints to the chief executive of BAA, Stansted's parent.

BAA has been criticised by airlines and passengers recently because of delays at its biggest airport, Heathrow, following the August terror scare. The TripAdvisor survey underlined Heathrow's problems by voting it the world's least favourite airport, based on criteria including ease of navigation and clean toilets.

A spokesman for BAA admitted that the world's busiest international airport is struggling for breathing space, as 68 million passengers per year flow through a facility designed to handle 45 million flyers. The airport will be less of a bottleneck when the new Terminal 5, designed to take 30 million people per year, opens in 2008, he added. BAA is drafting plans to enlarge the central security areas at Heathrow, which became clogged in August when a temporary escalation in security guidelines forced the cancellation of around 2,000 flights. The airport is also hiring hundreds of new security staff.

Changi in Singapore was voted best airport. Terrorism is the biggest concern for travellers, according to the survey, with 44% saying it was an important factor, followed by natural disasters and bird flu.

Elsewhere in the survey, Ayr was tipped as an unlikely hotspot for global travellers. The seaside town in western Scotland was voted one of the world's top 10 "hot" destinations next year, achieving a higher ranking than Marrakech in Morocco and the Greek island of Naxos in research based on web searches and travel site postings.