I'd argue environmental variables have the strong advantage in that you can use them in cases that won't otherwise expand, namely programs that take a path parameter immediately following an equals, e.g.

    $ docker run --workdir=$dev foo

in these cases `--workdir=~dev` is not expanded and fails as docker does not understand your alias.

True and I often have both. I like my exported environment variables to be all caps and my directory aliases to be lowercase. This keeps their uses separate.