I understand that "hours of enjoyment" can get extreme with addictive personalities and I think it's super relevant to point out games that use tactics specifically to trap users and extract in-app purchases from them but...

As a general rule I think "hours of enjoyment" is about as optimal as you can get for leisure payoff, the alternative "how much I learned" is nice too, whether that's literal stuff (like trivia), strategic growth or else can vary on a title-to-title basis.

But I do understand where you're coming from.