The answer to this really depends on what you want one of these devices for. It's worth weighing up Fitbit or Apple Watch though as they are both high-quality wearables, however the Fitbit is, as the name suggests, designed specifically to track health and fitness.
Earlier in the year our fitness editor conducted a thorough Fitbit Inspire 3 review, and scored it a solid four out of five stars. It's highly affordable, much more so than the Apple Watch, and so if fitness if your focus, and you're on a budget, the Fitbit is the way to go.