Apple
To put it bluntly, if you need a new phone because it's become too slow for your day-to-day use, it's time to upgrade. Just get any iPhone that's right for you - iPhone SE, iPhone 6S, iPhone 7, iPhone 8 or iPhone X. Don't worry about next year's iPhones.
If you can wait, though, a few rumors have already popped up if you're curious about what Apple has in store for 2018.
The rumors so far circle mostly around the next-generation iPhone displays, which could tell us that a design overhaul is imminent, at least for the successors to the now "mid-range" iPhone 8.
So far, however, there's no indication as to the 2018 iPhones' nomenclature. It's still wildly unclear whether they'll be called iPhone 8s or iPhone 9. We'll just call them the "2018 iPhones" for now.
It's important to note that these rumors are very early, and there's plenty of time for Apple to make changes over the next year until it announces its new iPhones in September 2018. And that's considering if these rumors are even true in the first place. Take everything here with a grain of salt.
Check out what the 2018 iPhone rumor mill has in store so far: