The most important KPI should be employee satisfaction
It is a common misconception that the most important KPI in a business is customer satisfaction. I am sure a lot of managers will fall out of their seats when reading that sentence. But I am serious.
What I mean is: Customer satisfaction is important. But it is more important how your employees are feeling. It is not really that complicated. If you have employees who thrive, feel seen, heard and successful, they will work better. And that means that your customers will receive the best possible service, deliverable or product, and that will improve your customer satisfaction score. Success breeds success.