I personally use fish, but mostly for the out of the box auto completions and highlighting, I don't use it for actual scripting, nor have it set as the login shell due to the 2nd reason you mentioned.

I mostly use python as well, and for some short commands I made pyxargs [1] which lets you run python code on stdin, or a walk of your current directory.

[1] https://github.com/elesiuta/pyxargs