If the devs behind Charles would just tweak their UI a bit, it would be the absolute perfect tool. Functionally it pretty much already is. Mainly being able to turn on and off and configuring features I use all the time (rewrite, map local, map remote) is always a journey through menu's that don't always make sense. The only functional thing I'm missing is some DNS stuff (e.g. throttling or breaking DNS specifically).
I tried using proxyman for a while, and while definitely powerful and more modern, it honestly didn't feel "better" or more powerful so I didn't go for yet another license.