Whoop 4.0

The Whoop 4.0 is a screen-free, subscription-based performance tracker focused on recovery, strain, and sleep. It provides a detailed analysis of your body's readiness through metrics like Heart Rate Variability (HRV), resting heart rate, and respiratory rate.

Its key feature is the Strain Coach, which recommends daily exertion levels based on your recovery score. Targeted at serious athletes and data-driven individuals, it requires a monthly membership. It ranks highest for its unparalleled focus on physiological data and actionable insights, though the lack of a display and ongoing fee are considerations.