Favourite country: Scotland. Favourite airport: Singapore. Favourite city: Vancouver. So far, so predictable. But occasionally I am asked for my favourite airline, and the response is often taken as sheer affectation: Ryanair. Yes, the airline whose boss, Michael O'Leary, is delivering “customer service” in the shape of ever-steeper fees for checked-in baggage - and even talking of charging for cabin luggage.

There is plenty not to like about the Ryanair experience. I resent the way that the booking process seems to be constructed as a series of traps for the unwary, with a new twist: before you can even start surveying fares and times, you have to sit through an advertisement at the “security check” stage, where you also have to tap in a code to prove you are a human being rather than an automated screen-scraper algorithm.

Ryanair was late to the online booking game, persisting with travel-agent and telephone sales while easyJet.com was thriving, but now sees the internet as the first opportunity to flog “ancillaries”, starting with a £1.69 charge for a text confirmation.

Why pretend to offer me a “discount” for paying with a debit card, rather than portraying the reality that Ryanair – like its rivals – levies a credit-card surcharge? And if I want to buy overpriced travel insurance, I’ll ask for it, thanks; but the airline’s website requires me to know that I have to scroll down beyond Slovakia on a drop-down list in order to select “Travel Without Insure”.

In the event that you successfully buy a flight without unwittingly picking up a host of unnecessary extras, your problems are only just beginning. Both Ryanair and easyJet instruct passengers that they must print out a boarding pass in advance. But if you fail to do so, then easyJet will issue one for you at the airport free of charge. Ryanair will levy what looks like an on-the-spot fine: £70. Penalties for marginally exceeding cabin-baggage dimensions or weight are of a similar magnitude. The airline insists these are purely to encourage every passenger to toe the line, keeping the operation running at peak efficiency. But they also help Ryanair extract an average £6 profit from every passenger.

So how can I possibly admire an airline that makes travel so uncomfortable? Because Ryanair does something so important that its sins should be forgiven. The Irish carrier delivers safe and punctual air travel at average fares that are way below the norm, and therefore enfranchises a mass of travellers who previously were confined to overnight bus journeys from Dublin to London or Krakow to Manchester. Michael O’Leary did not re-invent a failing airline as an ultra-low-cost carrier in order to unify Europe, but that is what he has done much more successfully than any EU initiative.

Even if you are one of the many who say “I’d never fly Ryanair,” every air traveller in Europe benefits from its existence. While O’Leary’s claim to be in competition with British Airways is sheer bluster – the two compete directly only on a tiny handful of routes from Gatwick – the downward pressure on fares has forced all the previously over-priced “flag carriers” to treat their passengers with more respect.