After entering the market a handful of years ago, it appears that smartwatches are finally hitting their prime. The wearable devices industry is projected to grow to an incredible $17.4 billion by 2021; in which it is estimated that around 81 million smartwatches will be sold.

Thanks to their burgeoning popularity, smartwatches are available from more brands — and with a greater variety of features — than ever, so buying one can be confusing. So, what’s the best way to zero in on a smartwatch that works for you?

With options from several leading technology brands, it’s easy to feel overwhelmed. A great place to start is by familiarizing yourself with the most popular and useful smartwatches on the market today. Read on to learn the basics about seven of today’s top-selling smartwatches — but make sure to do your due diligence before actually pulling the trigger and buying one.

1. Apple Watch Series 4

Price: $399

Battery Life: 1 to 2 days

Compatibility: iOS

With its massive, 1.78” screen and plethora of fitness tracking options, the Apple Watch 4, which debuted in 2018, is definitely worth a look. Water-resistant up to 50 meters, the device is compatible with Wi-Fi, NFC, and Bluetooth. Plus, an LTE-connectable version is also available.

Activity rings on the primary display encourage you to keep moving and meeting your goals throughout the day. Track activities ranging from running to swimming to yoga to strength training with ease. New to the device is automatic exercise detection, which automatically starts tracking exercise after it has been detected. Heart rate monitoring is still exceptional, and a future update will add an ECG feature that checks for atrial fibrillation.

With 16 GB of storage, the Apple Watch 4 serves as much more than just an activity tracker. Unfortunately, one thing it is conspicuously lacking, however, is sleep tracking.

2. Apple Watch Series 3

Price: $279

Battery Life: 18 hours

Compatibility: iOS

Offered in an 8 GB, non-LTE version and in a 16GB, LTE-connectable version, the Apple Watch 3, which debuted in 2017, is a more affordable yet very high-quality choice for people who want fitness tracking and more. Battery life is strong with an average of 18 hours per charge, but the battery tends to drain quickly with LTE enabled. Like the Apple Watch 4, this one is water resistant up to 50 meters and can track dozens of different activities. It goes above and beyond in terms of heartrate monitoring, tracking your resting heart rate, workout heart rate ranges, and other metrics.

With its highly accurate GPS, the Apple Watch 3 is especially useful for runners. It also works with enabled gym equipment, and it effectively tracks high-intensity interval training, or HIIT, workouts.

3. Fitbit Ionic

Price: $250

Battery Life: 2 to 3 days

Compatibility: Android and iOS

Fitbit’s full-fledged entry into the smartwatch world, the Ionic is a terrific smartwatch for active types. It automatically detects and starts tracking several different exercises, and it is water-resistant to 50 meters — therefore suitable for swimming workouts too. Equipped with GPS and a heart rate monitor, it can last up to four to five days on a single charge and for an average of two to three in general.

Few apps are available for the Ionic so far, and its interface is a bit laggy. However, Fitbit will add a feature for tracking blood oxygen levels soon, which will be nice. Plus, it will also later include support for tracking blood glucose levels — a revelation for those who suffer from diabetes.

Another great feature is Fitbit Coach, which keeps you motivated and progressing. Audio workouts for this feature are coming soon.

4. Fitbit Versa

Price: $200

Battery Life: 3 to 4 days

Compatibility: Android and iOS

A step down from the Fitbit Ionic, the Versa offers an attractive price point and a wealth of exciting features. It includes 2.5 GB of storage, which is a lot less than what you will get with an Apple smartwatch but still ample. The device is equipped with Wi-Fi and Bluetooth connectivity, but it doesn’t offer GPS. You can use the Versa to track all major workout types, which all have dedicated tracking modes.

The Versa is especially useful for tracking swim workouts, and it is water-resistant up to 50 meters. Workout summaries bring you up to speed about your accomplishments and weak spots, keeping you motivated and on track. The device includes sleep tracking, and it is also loaded with Fitbit Pay, which allows you to pay for goods on the go.

5. Samsung Galaxy Watch

Price: $329

Battery Life: 4 days

Compatibility: Android and iOS

One of the most highly rated smartwatches on the market today, the Samsung Galaxy Watch is available in 1.2-inch or 1.3-inch display sizes. Featuring 4 GB of storage, which is more than ample for most, it is loaded with dozens of built-in workouts that you can follow along. Six exercises can be detected and tracked automatically, and there are 39 in total. Naturally, the device is water-resistant up to 50 meters, and it charges wirelessly

The Samsung Galaxy Watch offers sedentary reminders and sleep tracking. You can always navigate to the “Together” tab on the device to challenge a friend to a one-on-one competition to see who expends more energy per day. The device also includes a stress management tracker that is supposed to detect when you are too stressed and to offer breathing exercises for you to follow, but it leaves a bit to be desired.

6. Samsung Gear Sport

Price: $299

Battery Life: 5 days

Compatibility: Android and iOS

Like the Samsung Galaxy Watch, the Gear Sport boasts a cleverly designed rotating bezel that is used to navigate through its menus. Water resistant up to 50 meters, it is suitable for tracking swimming workouts along with dozens of other activities. Like the more expensive model, it also offers stress monitoring and sleep tracking.

With a battery that lasts for up to five days on a single charge, the Gear Sport is one of the longest-lasting smartwatches on the market today. LTE connectivity is available but only through T Mobile; if you use a different carrier, you are out of luck or will need to switch. The 1.2-inch display is nice and bright, and the device includes GPS and heart rate monitoring.

7. LG GizmoGadget

Price: $150

Battery Life: 2 days

Compatibility: Android and iOS

Rounding out the list is the LG GizmoGadget, which differs from the others in that it is geared toward children. If you are a parent who wants to encourage your kid to be active, this smartwatch may be the answer. Its large 1.3-inch display and easy-to-use interface make it great for kids, and it even includes a few fun touches — a voice changer and a button that makes funny noises — to keep younger users engaged.

The LG GizmoGadget has a GPS, but it does not include a heart rate monitor. It includes a variety of features that can be used for workouts, including an activity tracker, a timer, and a stopwatch. You can also set up parental controls on the device if you are concerned about how your child may use it or what they may access.