Expedia Group Senior Director of Product, Head of Trust and Safety | Formerly Amazon • 4y
This could really range based upon the company, your users, your target goals, where you are in your business lifecyle, etc.
The most basic ones are: acquisition, activation, retention, revenue, referral
You could also be measuring customer lifetime value
In regards to the worst KPIs, honestly those that cannot be discretely measured and tracked over a specific time period. Vanity metrics (e.g. the number of views from a marketing article or number of shares of a post) really add no value.