In the few conversations I've had, it's always been revenue. This provides an incentive to spend lots of money on user acquisition, even if doing so means losing money (or not making as much).

I wish there were a standard assumption that if a business is profitable, then we use profit instead of revenue, and (crucially) use a much larger multiplier. It feels like I'm always having to remind folks that revenue ≠ profit, and that normal guidelines (we invest in companies with $X00,000 revenues) might need to be adjusted for smaller, breakeven or profitable businesses.