3 reasons you should buy the 2-year-old Apple Watch Series 3 over the new Series 5

If your primary reason for purchasing an Apple Watch is to track fitness metrics and receive notifications when you're away from your phone, the Apple Watch Series 3 will do just fine.

Like the Series 5, it can measure your heart rate, monitor workouts and activity, deliver notifications for text messages, phone calls, and apps to your wrist, and run apps.

It shares many of the same sensors and capabilities as the Series 5, including GPS for location tracking, a barometric altimeter for measuring elevation during workouts, a speaker and microphone for making phone calls and using Siri from your wrist, an optical heart rate sensor, a gyroscope for determining the watch's orientation, an accelerometer for detecting movement, support for Emergency SOS calling, and water-resistance of up to 50 meters.

You don't have to buy Apple's newest smartwatch to get all of the Apple Watch's newest features. Apple's watchOS 6, the latest version of its watch software that launched in September, is compatible with Apple Watch models Series 1 through Series 5.

That means older watches like the Series 3 will still get new features like an App Store that works directly on the watch rather than requiring that you use your phone to install new apps, the ability to monitor fitness activity trends over time, support for monitoring hearing health, and menstrual cycle tracking for women.

While the Series 3 is an excellent deal for those who don't want to splurge on a $400 Apple Watch, it's worth noting exactly what you're missing by opting for a cheaper model.

The Series 5 is the first Apple Watch to feature an always-on display, which means that even when the screen is inactive it will continue to display its watch face. That makes the Apple Watch much more useful at its most important job — telling the time — since you'll no longer have to raise your wrist or touch the watch to activate the screen.

Apple's latest smartwatch also has a compass, which makes apps that rely on location data like Apple Maps all the more accurate. There's also support for international emergency calling on the Series 5, which could be an appealing addition for frequent travelers.

The Series 5 also retains the standout features that launched on its predecessor, the Series 4, which Apple no longer sells. Such capabilities include the ability to detect when the wearer takes a hard fall, an electrical heart rate sensor that can take electrocardiogram readings, a second-generation optical heart rate sensor, a faster processor, and a new design with a larger screen. The Series 3 lacks all of these improvements.

You'll also have much more choice when it comes to customization and color options if you opt for the Series 5, since the Series 3 is currently only available in the Space Gray or silver aluminum finish.

The Apple Watch Series 3 is an ideal choice for iPhone loyalists that want the overall Apple Watch experience but don't need all the extras that come with the pricier model.

If you primarily want an Apple Watch for catching calls and texts even when your phone is buried in your bag; closing your Move, Exercise, and Stand Activity rings each day; using Apple Pay without reaching for your phone; and getting basic data about your heart rate, the Series 3 is probably the right choice for you.

But if you're purchasing an Apple Watch for an aging relative, for example, you might want to consider the Series 5, since it comes with fall detection, more sophisticated heart rate sensors, and a larger screen that may be easier to see. Those who travel frequently may also be more interested in the Series 5 given its international emergency calling capabilities and built-in compass.