True cinnamon, Cinnamomum verum, aka Ceylon cinnamon, Cinnamomum zeylanicum is better for your health than the Cassia varieties commonly sold in grocery stores.

This because True cinnamon lacks significant quantities of coumarin in its composition while containing some health enhancing components. Here is one study that presents some evidence in this direction: Evaluation of pharmacodynamic properties and safety of Cinnamomum zeylanicum (Ceylon cinnamon) in healthy adults: a phase I clinical trial

The flavor is not quite as strong as that given by the Cassia varieties though, and it is a bit more expensive too, hence the popularity of Cassia cinnamons in grocery stores.

Anyone who consumes more than just a little bit of cinnamon on an occaisional basis would be wise to use True cinnamon.

True cinnamon is sold by Penzeys: Ceylon Cinnamon Ground

Whether you can find it in the grocery store depends on your grocery store.

This article may be helpful: Ceylon Cinnamon VS Cassia Cinnamon