Fly has a nice DX but unfortunately the platform still has major issues with reliability and networking. There are often problems with deploys leading to stuck and unreachable instances or other networking issues. It's probably exacerbated by the new user growth but the slick deploy workflow can't override having an app that works. Render and others are interesting but K8S is still fundamentally better considering al…
What exactly makes K8s better?
K8S offers the same primitives and more, with progressive complexity as you need it. You can deploy a single container with a 1-line command or an entire PaaS subsystem. It's also more portable than any single platform and you can run it on a few VPS instances or your own bare metal. I've also found it far more reliable than all these PaaS services that have their own issues with no visibility.
K8S experience is also more valuable and useful in future projects and there are plenty of nice DX tooling to make deploys easy if that's the blocker.