For me, the standout feature of the Sense 2 has been the ability to measure stress via an EDA sensor.
Fitbit Sense 2 review: a fitness tracker disguised as a smartwatch - The Verge
Fitbit's Sense 2 gave me a glimpse of how the Google Pixel Watch will be
Fitbit Sense 2 Review
Fitbit Sense 2 Advanced Health & Fitness Smartwatch
Fitbit Sense 2 review: Excellent health watch
Fitbit Sense 2 review: a fitness tracker disguised as a smartwatch - The Verge
Fitbit Sense 2 Review
Fitbit Sense 2 review: Great hardware, but difficult to recommend
Fitbit Sense 2 review