Docker would save resources if you could share the host kernel. On MacOS, you need to run docker-machine before you can run docker containers, so you will have a full Linux VM anyway. From that point of view, it should not make much difference, use whatever you like better.
If you use Docker for Mac it will use less resources because it will use the native hypervisor built into macOS and install a minimal OS on top of that. Much more light weight compared to a full VM under virtual box.