A utility function is quantitative, not qualitative.
How would you go about transforming these vague statements into precise mathematical definition?
(I'll grant you "black box rights"; you can use terms - anger, doubt, etc... - that humans can understand, without having to define them mathematically. So if you come up with a scale of anger with generally understandable anecdotes attached to each level, that will be enough to classify the "anger" term in your overall utility function. Which we will need when we start talking quantitatively about trading anger off against pain, love, pleasure, embarrassment...). Indirect ways of measuring utility - "utility is money" being the most trivial - are also valid if you don't want to wade into the mess of human psychology, but they come with their own drawbacks (instrumental versus terminal goal, eg).
Utility is the dot product of the derivative of desires and the observations. Desires are what you attempt to make happen.
If you start trying to make what's currently happening happen more often, then you're happy.
Some people see never-existed people as moral agents, and claim that we can talk about their preferences. Generally this means their personal preference in existing versus non-existing. Formulations such "it is better for someone to have existed than not" reflect this way of thinking.
But if the preferences of never-existed are relevant, then their non-personal perferences are also relevant. Do they perfer a blue world or a pink one? Would they want us to change our political systems? Would they want us to not bring into existence some never-existent people they don't like?
It seems that those who are advocating bringing never-existent people into being in order to satisfy those people's preferences should be focusing their attention on their non-personal preferences instead. After all, we can only bring into being so many trillions of trillions of trillions; but there is no theoretical limit to the number of never-existent people whose non-personal preferences we can satisfy. Just get some reasonable measure across the preferences of never-existent people, and see if there's anything that sticks out from the mass.