As soon as I start adding ifs and battling to remember the exact syntax I give up and move to Python and argparse. Recently I've started using the Begins[1] library to make useful command line tools and scripts even more quickly. I appreciate it's less and less portable at this stage but so much more productive. Most of the time these scripts are very specific anyway so it's not a concern.
The other thing I've noticed amongst peers is that I'm usually the only one (or one of a limited few) that remotely understand the shell script too. So I'd serve the team better writing it with Python. YMMV with that of course.