I want to bring people into existence to satisfy my own preferences. Of course, everything I want tautologically satisfies my own preferences, but I decide that bringing people into existence is good because of the value of their lives, not because they would have chosen to exist.
Good
I'd somewhat disagree with you (at least in the strong, repugnant conclusion form of your argument), but this is a much more defensible argument that ones that implicitly rely on the preferences of non-existent people.
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.