Some time ago I made a table with all ACC buttons, for labeling my button box & wheel buttons. Maybe this will give you some -easier to read- insight in what to decide. My only advice would be to at least have wipers, lights and pit menu navigation assigned. When you drive Pro mode, you will need ignition, engine start. Pit limiter I believe can be set to automatic if you prefer that. A button for toggling through the multifuncational display MFD is also worth it. Remaining are tc, abs, brake bias and engine map, but that depends whether you like to change these while driving.