If not vanity metrics, then what else?

Majority of startups are built on vanity metrics (GMV/ PV/ Downloads etc etc). But what do startups actually need?

Clarity metrics. and Sanity metrics.

Clarity metrics are operational metrics, like the number of minutes a day your product actually gets used or how long it took for a user to get service. These are the hidden gears that drive growth. Use them to solidify your competitive advantage.