Best & worst airlines - Wow comes last.

Here's the survey methodology so everyone can decide for themselves how much stock to put in a single survey with its own limitations and biases:
https://static.airhelp.com/pdf/AirHelp+Airline+Score+2018+Methodology.pdf
https://www.airhelp.com/en/airhelp-score/airline-ranking/

As with every survey, the criteria and the weights on each may or may not reflect the reader's preferences. In my case, I put much greater weight on on-time performance and much less on claim processing (mostly because I've really never had to submit one, in spite of frequent business and leisure travel. If you take only a carry-on, this is even less important). Since this survey sponsor is a third-party that helps others get compensation, this variable has a considerable weight because they have a lot of data collected internally on it. In any case, WOW is a relatively new airline with a different business model and it's customer service may be lacking a bit (ok, maybe a lot). It may take some years to work out the kinks. I wouldn't avoid it altogether - it's all about risk and value trade-off with budget airlines. I've flown several and feel like I've gotten very good value. They may not have been the most comfortable or had edible food, but the prices were very competitive to make up for those shortfalls.

PS. This survey excludes a lot of airlines by focusing on only the largest by passenger volume. 72 total is a fraction of the total population of carriers.

I've flown several budget airlines: Ryanair, Norwegian, Frontier, and some that are close to budget: LOT, Icelandair, etc. In general, I've been quite satisfied because I did my homework and knew what to expect. The online comments about Ryanair were quite frightening, but we followed the check-in and luggage rules and it was a breeze.

We flew on American Airlines from New Zealand and the first leg was perfect and then things went down in Los Angeles and it became a nightmare flight. On and off cancellations because of maintenance, long customer service lines at the airport with conflicting advice, and then running through the terminal to catch flights. Comparing my most recent long flight from CPH to FLL on Norwegian Air, I have to say the "budget" airlines won the prize, hands down.

I agree with Agnes. Wow has only been around like 5 years; it has growing pains but gets the job done. It is not for everyone and makes travel more affordable for people that love to travel, have a lot of flexibility, know what to expect and who can not afford Lufthansa or legacy carrier prices.

I still have claims pending for flights cancelled flying both Lufthansa (3 weeks) and Wow (6months). Airhelp wanted 25% to file my claim so I am doing it myself.

This survey does exclude Southwest, in spite of that airline being 3rd in terms of passenger volumes (more than United, which is part of the survey). Many airlines are excluded from the rankings, although there is a sound reason to compare apples-to-apples (airlines within the same class, as opposed to very small airlines carrying only relatively few passengers vs. the big behemoths carrying many more passengers). Again, all surveys should be interpreted in light of their limitations, including the percentage of the total carrier population covered by the survey. Findings should really be stratified by carrier size/volume so that small, mid, and large airlines (however that's defined) can be compared to their peers.
https://en.wikipedia.org/wiki/List_of_largest_airlines_in_North_America

For US airlines, I would rate the big three in this order:

1. Delta
2. United
3. American

Southwest is great if you need a bargain price, but I dislike their seat assignment policies.

We haven't flown on every foreign airline, but some of those that we regard as very good to excellent:

Korean Airlines
Cathay Pacific, never been on Singapore Airlines
Air France
Lufthansa
Virgin Australia

Some foreign airlines that I have found mediocre to poor
Iberia
Air Italia