@lotuslight what are you looking for from a continuous glucose monitor?
Do you have a recent smart phone or would you also be looking for a separate reader?
Will you need continuous readings all the time or will you be collecting data to adjust your lifestyle?
Do you also have a finger prick monitor? (CGMs do not replace the need for pricking your finger.)
Yes, there are at least two (I can think of 8 off the top of my head) but "the best" depends upon what you want to do with it and the data. And they do not all have to be worn on the arm.