Stripe gets the front page because they are popular with developers, but I've dealt with so many other more-corporate payment processors that are absolutely awful for reliability. Rampant downtime, terrible support, terrible concurrency limits, failure to meet SLAs, terrible documentation (900 page specs that are impossible to read). They all think they are awesome, and yet can't go more than 48 hours without having some system degradation email sent out. I don't want to name them, but they are some of the worst businesses I've ever dealt with. They just want to sit there and collect huge amounts of money for helping you connect to Visa/Mastercard/etc, and do little else.
Rage. Stripe hitting a little downtime is nothing in comparison.
I have some experience with a Stripe competitor (may have predated Stripe by a bit) but their reliability was probably on par, more or less. Their API though... would’ve been worth a couple lost 9s for a better API. Polar opposite of Stripe on that front.
I dealt with one that seemed actively hostile. They would change their API without any advance warning at all. Data fields that we depended on would mysteriously vanish in the middle of the day, causing our entire system to grind to a halt until we put in a hotfix. Happened several times in the two years I worked on that project.
Rage. Stripe hitting a little downtime is nothing in comparison.