I use both, as my Dexcom is paid for by my insurance and it is more accurate. I self fund the LIbre as I use it to ocean swim and I keep the reader in a water proof pouch and can actually scan it while swimming. I also used a Libre before my Dexcom.
The LIbre is wonderful and usually more economical. But hands down a Dexcom is better because you can calibrate it to make it more accurate. I can get my Dexcom with some calibrations to within .3mmol (5mg) of accuracy. Most of the time a LIbre is off by 1 to 1.5 mmols (20-30 mg) depending. Sometimes at the lower numbers it is closer, random ones can read better or worse. When I used a Libre I used to automatically add points to the numbers to get a more accurate number to dose by,
For dosing, it's an important difference for me. As soon as I am done swimming the Libre reader goes into my purse for storage. But if it's an economical decision a Libre is a blessing not to be ignored and is a wonderful thing to have........ it's just a Dexcom is better. I gather that the UK now has Dexcom One which is their more economical version to compete with the cheaper costs of the Libre. I don't think it is supposed to be different other than some ap variations.
Customer service is very important...........it's just really a Dexcom is better because of being able to calibrate it.