Summary: 4 screenless fitness trackers compared over 2 weeks

Michael Bryan tested Whoop MG ($199–359/yr subscription), Fitbit Air ($99), Amazfit Helio ($99), and Polar Loop 2 ($99).

Category winners:

• ❤️ Heart rate (intervals): Amazfit Helio, by far (R=.939). Whoop 2nd, Fitbit struggled, Polar worst.
• 👣 Steps: Fitbit most accurate (994/1000) but overcounts "phantom" steps; Amazfit tends to undercount; Polar least accurate.
• 😴 Sleep: Amazfit best, especially when traveling (time zones). Whoop close 2nd. Fitbit confused by the date line; Polar weak.
• 📱 App: Whoop best, Zepp (Amazfit) solid. Fitbit too much AI/text. Polar worst.
• 🔋 Battery: Whoop ~12–14 days, Amazfit ~8–9, Fitbit/Polar ~7.
• Comfort: Fitbit Air lightest; Polar most "premium" but strap frayed.

Verdict:

• 🏆 Everyday user → Amazfit Helio (accurate HR/sleep, good app, no subscription).
• 💪 Advanced athlete / health data → Whoop (ECG, blood pressure, deeper insights) if you pay the subscription.
• ⚡ Fitbit Air: solid pick if you want the thinnest/lightest + like its app.
• ❌ Polar Loop 2: not recommended despite the nice design.