I used to have a bunch of over-complicated aliases, but due to their limitations, I now use a mix of aliases and functions, with a few scripts in ~/bin. It’s all a matter of using the right tool. I use aliases for simple things, like default options on some commands. Things that need to happen in the current shell, but are too complex for an alias, are functions. That leaves extra-complex things that I don’t want to write a shell function for as programs in ~/bin, which can be shell, or python, or whatever.

Less portable and don't give the subprocess isolation that a proper script has. That's sometimes an advantage (can modify shell state — I think that's the primary one), sometimes a disadvantage (influenced by shell state [e.g. set -e], "exit" exits the entire shell, hard to do cleanup / use signal handlers, can accidentally change shell state [like cwd].)

But I'd use a shell function over an alias if a script isn't an option.

Similar problems.