Tech Which Apple Watch to get: How the cheaper Series 3 and SE compare to the new Series 6 September 17, 2020September 18, 2020 Jefferson Graham, USA TODAY Comments Off on Which Apple Watch to get: How the cheaper Series 3 and SE compare to the new Series 6 The key health features like blood oxygen and ECG are on the top of the line Series 6, not the SE or Series 3.