The circulatory system, as it circulate the hemoglobin which contains the oxygen you need to survive, everywhere in you body.
It wouldn't be nervous, because this is what regulates you thoughts, the impulsions of your actions etc. but it's main function is more like giving orders than executing.
Respiratory gets the oxygen but cannot give it, for example, directly to your kidneys, the circulatory system is the intermediate between those two.
