With our words.
Many homebrew review problems do an excellent job, in their texts, of describing what balance is being sought. Maybe it's spotlight-time, maybe it's combat effectiveness, maybe it's rewarding a particular style of play.
When a question is well-posed like that ^^ it's easy for voters to read answers, filter them through their experience, and ...
Some excellent guidelines on how to answer a homebrew-review question already exist
How to properly review a homebrew?
I believe these guidelines give excellent ways to tackle these seemingly incredibly subjective questions in more measurable and tangible ways. Many of the guidelines found there can also apply to house-rules questions:
One can compare a ...