> What is the edge that docker provides these days?

hub.docker.com mainly, the centralized docker registry. A bit like Github, there are plenty of alternatives. But that's where you find most people pushing their containers.

And then there is Docker Desktop which a lot of users seem to like.

I switched to colima myself recently (on a mac). I think people overthink all this stuff a bit. Colima doesn't have a UI; but that's fine for me. I mainly use it to run stuff from the command line or from scripts. I wasn't using the Docker Desktop UI very much either.

Colima is a simple wrapper around Lima, which is a simple wrapper around qemu or Apple's virtualization layer. The resulting vm runs a simple Linux distribution with some file mounts and network tunneling to give you a similar experience as Docker Desktop. Which does exactly the same thing in the end of course.

Linux runs containers just fine. The main thing you need for containerization is a Linux kernel. People have actually hacked together docker alternatives with just bash and namespaces. I used a plain qemu vm for a while with the docker socket pointing to an ssh tunnel on my mac. Works amazingly well but it has some limitations. Colima is easier to manage.

People have mentioned several of the other alternatives already. They all can work with the same command line tooling. If you need a UI, colima is probably too barebones. But otherwise, things like IDEs and other tools work (e.g. lazydocker, vs code, intellij, etc.) just fine with it. So the added value of extra UI is limited to me at least.

I think the container runtime inside the vm (podman, containerd, whatever) is mostly not that relevant for developers. It's a bit of an implementation detail. As long as docker and docker compose work on the command line, I'm happy.