Short answer — best-in-class choices by need:

• Best for iPhone users / best all-round sports watch: Apple Watch Ultra 2. (Apple.com)
• Best for serious runners, triathletes and wilderness endurance: Garmin Fenix / Epix family (Fenix 7 / 7 Pro or Epix Pro) — far superior battery, maps and advanced training metrics. (TechRadar.com)
• Best budget/value fitness tracker with solid features: Amazfit (Active 2 / Balance) — good GPS, long battery and low price. (theverge.com)
• Best lightweight tracker for focused health metrics: Fitbit Charge 6 (or Versa 4 if you want more smartwatch features). (tomsguide.com)

Why these (quick comparison of the most important fitness factors)

• Sensors & metrics: Apple Ultra 2 and Garmin Fenix/Epix include advanced GPS (multi-band/dual-frequency on Apple; multi-GNSS + multi-band options on Garmin), accurate optical HR, swim metrics and multisport/transition recording. Apple adds deep iPhone/Health app integration and safety features; Garmin adds richer endurance/recovery metrics and mapping. (Apple.com)
• Battery life: Garmin Fenix/Epix (especially solar Fenix variants) run days–weeks in smartwatch or GPS modes (best for multi-day outings). Apple Ultra 2 is stronger than standard Apple Watches (~36 hrs normal, up to ~72 hrs with low-power modes) but not as long as Garmin. Budget Amazfit/Balance models often last a week or more. (TechRadar.com)
• Ecosystem & apps: If you own an iPhone, Apple Watch gives the smoothest experience and best third‑party app support. Garmin and Amazfit are more platform-agnostic (Android + iOS), but Garmin Connect is best for deeper training analysis. Fitbit focuses on simple health dashboards and sleep tracking. (Apple.com)
• Durability & outdoor use: Apple Ultra 2 is rugged (titanium, WR100, dive‑rated) and great for everyday + adventure. Garmin Fenix line is built for backcountry use, long expeditions, and heavy-duty battery modes. (Apple.com)
• Price / value: Ultra 2 is premium (typically $699–$799+); Garmin Pro/Fenix models are premium to high-end ($500–$1,300+ depending on model and features); Amazfit offers the best low-cost feature set; Fitbit sits in the affordable to mid-range segment. (Apple.com)

Which to pick (one-line guidance)

• You have an iPhone and want the easiest, most polished fitness + daily watch: Apple Watch Ultra 2. (Apple.com)
• You train seriously (marathon/triathlon/ultra/hike) and need max battery, maps and advanced training/recovery: Garmin Fenix or Epix Pro. (TechRadar.com)
• You want the best fitness bang for your buck or a long‑battery band: Amazfit Active/Balance series. (theverge.com)
• You want a small, comfortable tracker focused on health and sleep with basic GPS: Fitbit Charge 6 (or Versa 4 for a larger screen). (tomsguide.com)

If you want, I can:

• Recommend a specific model and size for your wrist, budget and primary sport (running, cycling, triathlon, weightlifting, swimming).
• Compare two models side‑by‑side (battery, GPS modes, sensors, app features, typical price).

Which would you like me to do next?