The Apple Watch Series 9 and Series 7 are two of the best smartwatches iPhone users could buy. Not only do they offer seamless interoperability with iOS 17, but they also pack some advanced sensors that can help users track their health and fitness. Though, if you’re already using an Apple Watch Series 7, is the upgrade to a Series 9 worth it? Furthermore, if you don’t own either of these models, which one should you opt for?