Assuming your monitor is calibrated: if it looks good, then it's good.
If you want to go more high-tech, then the cards and such work too.
Often I go by the eye. If it looks wrong, I tune the sliders. Also it's bit subjective, so many times I switch between couple photos, and tune until they all look good. If you stick only to one photo, often after tuning it to "look good", and you come back later, it doesn't look good anymore.