I was so relieved to never need VM’s again after discovering Docker.

I would vote for docker as well. The last time I had to inherit a system that ran on virtual machines, it was quite a pain to figure out how the software was installed, what was where in the file system, and where all the configuration was coming from. Replicating that setup took months of preparation.

By contrast, with Docker, all your setup is documented. The commands that were used to install our software into the virtual machines and were long gone are present right there in the Docker file. And building the code? An even bigger win for Docker. In the VM project, the build environment for the C++ portion of our codebase was configured by about a dozen environment variables, none of which were documented. If it were built in Docker, all the necessary environment variables would have been right there in the build environment. Not to mention the build commands themselves would be there too, whereas with VMs, we would often have developers build locally and then copy it into the VM, which was terrible for reproducibility and onboarding new developers.

That said, this all comes down to execution - a well-managed VM system can easily be much better than a poorly managed Docker system. But in general, I feel that Docker tends to be easier to work with than a VM. While Docker is far from flawless, there are a lot more things that can make life harder with VMs, at least from my experience.