I rarely use either one and have perfectly healthy teeth and gums. I believe in cleaning from the inside rather than the outside. A diet, like one rich in fruits and veggies, that rids the body of toxins and supplies nutrients to your gums and teeth so they can fight off disease all on their own.
Mouth wash is much better in killing bacteria and more effective. Warm salt water is good when you have some bleeding and nice to have cleansing.
A pause from Mouth Wash vs Warm Salt Water to share interesting fact from one historian to you:
Today is: 16th December (GMT), in history on the 16th of December, 1830 AD the following birth happened:
John Frederick Hartranft: Bvt Major General (Union volunteers), died in 1889