The Apple Watch Series 5 is so far ahead of anything that professes to be a peer, there’s only one reason not to buy one: You want multi-day battery life. Otherwise, you’re not going to find a smartwatch with a better screen, more advanced sensors, nicer design, or stronger app support.
Apple haters will scoff at that notion, but the truth of the matter is, if Apple offered an iPhone-free version of the Series 5 watch, it would instantly become the best selling Android wearable.
If you have a Series 4, you’re probably not upgrading to the 5 unless you really want that always-on display and/or the compass. But, if you have a 3 or earlier, the Series 5 is a big step up and worth the price.