The phrase "choose your battles" conceptualises encounters as adversarial.
Any suggestions for less adversarial alternatives?
Distilling the central meanings from the "battles" idiom, the phrases "save your strength" or "don't waste your time" comes close without invoking confrontation or combat. They could even be used together.
Or, as an alternative, someone might "consider the cost" and ask themselves "Is it worth it?".
God, grant me the serenity to accept the things I cannot change,
Courage to change the things I can,
And wisdom to know the difference.
They are not equivalent, of course. The Serenity Prayer advises against entering into battles that you cannot win, while “choose your battles” more broadly discourages engaging in conflicts where the risk (or even the cost) is too high and/or the expected benefit is too low.