What are you using for a mouse?

[Flogs]

I use a Logitech MX Master 3s as it's fairly large so cups into the palm of my hand nicely and its various buttons lend nicely to keyboard shortcuts. I've set it up for different apps but mainly for Logic Pro so the back button opens mixer, forward button opens piano roll, small top button to duplicate regions, mouse wheel button press plus mouse forward/back to zoom in/out, thumb button to show hide virtual instruments and side scroll to side scroll.
I use a Magic Trackpad for its various features and it is ideal as an X Y pad but I always end up reverting back to the mouse for its shortcuts.

If you use a Mac, an iPad can act as a second screen, if you mirror the screen then a pen can be used as a controller but it is quite fiddly as the cursor disappears from the screen unless you keep the side of your hand on the iPad screen.

[zerocrossing]

The hands down winner is the Kensington Expert Mouse, which is not a mouse at all, but a trackball.