DASH vs Xonsh (The Xonsh Shell)

Dash has a very fast startup, this happens because the shell is started a lot of times during boot and dash minimizes the work it does during this process.

It is designed to be very lightweight and has no support for shell specific extensions that are not POSIX.

DASH is the default shell for Debian based systems due to it speed, full POSIX compliance and low overhead.

It's fully POSIX compatible, so if your script runs on dash it will probably run on all other shells.

It's a clone of the original System V4 Bourne shell.

Xonsh uses a syntax which is a superset of Python 3.4 plus some additional shell primitives. Because of the similarity to Python, which is famously an easy to understand programming language, the syntax of Xonsh is pretty easy to grasp too, even more so for Python programmers.

The xonsh shell has AppImage that makes it Linux-portable.

Most parts of xonsh are extensible. You can change tab-completer, prompt, history backend, aliases, functions and pack it to special package (called "xontrib") and put it on Github. The logic are clear and documented well.

Xonsh has one feature that can be considered particularly unique. It stores not just the commands you type, but their output, and doing a search on your history (configurably) can search the output as well.

Xonsh has native cross-platform support.