1. Prime security - Security is the most primary thing people should consider as to choose a payment gateway.
It's a common belief that most of these platforms have got the best of their security for their system. If there's a way to know their security provider then that's better if they disclose it but most likely, they won't.
And they're of great security until they're breached. We saw big companies and not just limited to payment gateways but anything related to crypto, many have been attacked and hacked.
So, talking about security, yeah there could be those companies that are having a prime and tight security but always think of it that they're secured until the unexpected happens.