I try to fly with Skymark when I can because their website is gloriously basic in the best way possible, it's like barebones server-rendered HTML. And you can book your ticket without payment being in the critical flow. You get like 24 hours to pay and that removes SO much stress from booking airline tickets. I hope they never change or "modernize" it with some shitty JS framework.
ANA’s domestic reservation system is not too bad in my experience, and I think is similarly basic like Skymark. They also allow you to hold a reservation for 24 hours without paying, and cancellations are free I think even after you’ve paid. It does struggle a bit with the concept of middle names, though.
But ANA’s international bookings use a completely different system that is the single worst website that I’ve used in the past 20 years. And yeah part of it is that they’ve tried to add some javascript without having the requisite competence to, say, perform proper input validation or render server error messages to the screen properly. I recently needed to enter an address, for example, but when I clicked the submit button nothing happened. It was only by snooping around in developer tools that I realized the server didn’t allow dashes in this particular address field.
Edit: apparently ANA is “upgrading” their domestic booking system to use the same Amadeus platform their international bookings use starting May 19, 2026. You can clearly see a different booking flow depending on whether you search before or after that date. So I retract my earlier positive statement about their domestic bookings.