I built the Stripe integration for a medium sized online retailer, and our experience wasn't quite as good as this. Our COO could get them on the line to negotiate our contract, but our engineers struggled to get useful answers out of them via email and our account manager often took weeks and multiple pings to respond to product questions.

I have had amazing success chatting with their engineers on IRC, but it's fairly unofficial, they're limited in what they can do when things concern user data, and I don't think most customers should need to get on IRC for support.

As for competitors though, I've heard from a customer "Stripe treat taking payments as a business, $competitor treats taking payments as a hobby". On balance, while not perfect, I'd probably choose Stripe again, but I'd get an account manager ASAP and try to build a good relationship with them rather than treating it as a black-box SaaS product that I don't need to interact with humans to use.

I believe that Stripe EOL'd IRC support when Freenode imploded. They've got a Discord, but I've heard that it's harder to engage with engineers there than IRC because of the volume of "general support" chatter.