BODY WEIGTH SCALES

Accuracy & consistency: A scale should reliably show your weight no matter how you stand on it. According to Consumer Reports, “ultimately … bathroom scales need to do only one thing really well: measure your weight.” 
Consumer Reports
+1

Weight capacity and increments: Make sure the max weight capacity is sufficient for you (and any other users). Also fine increments (e.g., 0.1 lb or 0.05 kg) give better resolution. 
Humblebee & Me
+1

Metrics beyond weight: Many modern “smart” scales measure body fat %, muscle mass, water weight, bone mass, BMI, etc. 
Health
+2
Kinetik Wellbeing
+2
 But note: many of these extra metrics may be less accurate than the basic weight measurement. 
Consumer Reports
+1

Connectivity & app support: Smart scales may provide Bluetooth/WiFi sync, multiple user profiles, trends/graphs, app integration with health/fitness apps. 
Tom's Guide
+1

Build & usability: Platform size, scale stability (especially on different floor types), display readability, safe materials (e.g., tempered glass) matter. Also ease of switching units (lb/kg), user recognition, etc.