Mouthwash is not essential and should not replace good brushing and flossing.
Mouthwash can be helpful if you feel you have bad breath. Any mouthwash can aid in cleaning the surface of the tongue and decreasing the smelly sulphur producing bacteria on your tongue.
But don't rinse straight after brushing as you will rinse off the toothpaste and the fluoride won't have time to work. Wait 30mins.
A mouthwash containing chlorhexidine (such as Savacol), works the best at decreasing bacteria that cause holes in your teeth, cause gum disease and cause bad breath.
The latest protocol for this type of rinse is to use daily for 1 week and then stop for 3 weeks. The effect of the chlohexidine will continue beyond one week and this protocol will also help to prevent you developing staining on your teeth. Repeated use of Chlorhexidine containing products can lead to a superficial staining on your teeth that can be cleaned off, but only with a scale and polish at the dentist.