After thinking long and hard about this very question a few years ago, this is the utility function I decided on.
Good time - this isn't just about fun and games. This is about making time and being present for the most banal moments. People I love - that includes family, and friends, and also me. This means that if an activity is making me feel alive, I will do it, even if other payoffs may be elusive to nonexistent.
This segues nicely into people I don't know, because I think one form of care is teaching others what you know. So I spend a fair bit of time writing stuff I don't have to write, with no other personal benefit to me other than maybe helping other people get to that endpoint a bit faster. (I might gain some residual benefit as being perceived as a domain expert, but you could achieve that with zero-calorie social media posts as well, instead of investing all this time writing articles).
Like any utility function, this one comes with costs. For one, I'm probably not maximizing my earnings potential, and I often have to remind myself that making more isn't a value in its own right.
For sure, I don't always live up to my lofty goals. All the same, I find a succinct utility function helps serve as a compass for a lot of the decisions on how to spend time.