Maximize societal benefit per tax dollar spent.
Find one policy in which this does worse than the status quo in the United States. If you want an easier task, change it to:
Maximize long-term economic growth per tax dollar spent.
I still suspect you cannot find an example of how this is worse than current policy. For instance, on the environment, the only path that makes sense on a 20-30 year timeline is to internalize the costs of externalities. That would force cleaner energy or environmental remediation, which would save lots of costal cities in the US, and lower losses due to crop failures and cities burning down. It'd raise the price of gas by maybe $1-2 vs pre-Iran prices.
Speaking of which, we'd never have gone into Iran because there was no economic story for it.
Education is cheaper than prisons and also leads to higher expected growth. Universal health care lowers wasted work on insurance paperwork (which is currently > 33% of US health care costs).
Then there's stuff we wouldn't do: How exactly does policing bathroom gender policies grow the economy again? Allowing food manufacturers to add known poisons to food? Jailing farm workers + their children?
And so on.