Assuming you have checked for insurance coverage, since Dexcom is generally higher cost. Some insurance will cover as pharmacy and if so, is usually lower cost and easier to get filled.
And as of now, G6 is the only option for new purchase, which I assume you planning on.
First thing is what you plan to use for seeing readings/alerts ? Dexcom website has limited android phone support, in addition to Apple. Many android users accommodate this by using xDrip. Or you can use the dexcom receiver.
For cost saving, many use sensors after they end. Many good topics here that explain how to restart them.