I'm still using my Samsung Galaxy S7 which I've had since 2016. Replaced the swollen, non-replaceable battery in it twice but it still keeps ticking. I haven't even thought about a replacement phone. The S7 does whatever I need it to do so I'll keep it until it dies.
I've had a Galaxy Note 9 for coming up on two years now. I pre-ordered it. Love it. Haven't had the same freezing and slow down issues of older phones. Will probably keep this for at least another year pending any issues.