I ran my Galaxy Note 3 up until less than a year ago(daily driver). Still on Android 4.4.x too (Android 5.x was a downgrade in my opinion). It was my first Android device, prior to that I used WebOS. VERY reluctantly switched to Galaxy S8 Active(still new) last summer as the phone I thought sucked "the least" of any phone on the market.
I have two Note 3s and one Note 4.
I'm taking every precaution I can to try to ensure it lasts as long as it can. Including having a backup phone, having replacement OEM batteries(though I dread the thought of having to get the battery replaced), and invested in two devices called "Chargies", which sync with bluetooth to my phone to ensure the device doesn't go beyond a given charge level (for me that level is 79%), provided it is connected to a charger with Chargie connected. Add Accubattery to that list as well.
I happily replaced the batteries in my Note 3s (one of which is still in daily use, though uses Android 5, it's really only used to view slack) every year because well it was easy. I never needed user replaceable batteries on a daily basis but being able to safely replace them myself annually was a big selling point(keeps things fresh).
Plastic back, wireless charging(I have been wirelessly charging since the original Palm Pre), flat screen were the biggest selling points for me on the S8 active. The bigger battery is nice too as that implies the life will be longer.
Currently on Android 9, which is a downgrade over 8, in fact at least for me every newer release of Android takes away more and more things and is a downgrade. If I wanted an iPhone I'd buy an iPhone.
Other than faster performance the S8 Active doesn't really do much that my Note 3 didn't do already(and in many cases better).
I'd happily drop $2k for an up to date Note 3 with plastic back, wireless charging, removable battery, flat screen, with Android 4.4.x look & feel & control.
I'd also happily pay a subscription fee to get those fancy security updates for the older OSs, so I'm not forced into upgrading to a major version of android to get fixes. But that isn't available either. I'll take no fixes and a more usable phone 100000000000000x more than the latest updates given the history of things. I am also careful about what I use my mobile devices for, no social media, no banking, and the only purchases I do are with virtual credit cards generated by my computer. Also have had the android auto download of MMS disabled for years, I do not open MMS from people I don't know (which isn't a guarantee on anything but goes some ways to improving security regarding the exploits in the android media framework). Not perfect, but at the same time I am not aware of any security incidents on my mobile devices ever (same goes for my desktop and laptop devices(mostly running linux).
Things I miss about note 3 include the stylus, user replaceable batteries, the IR blaster, Android 4.4 experience, having more control over the OS (e.g. can view cpu usage per task and kill stuff etc), MHL (not sure if the S8 active does that or not). IR blaster and MHL I only use while traveling, and I still bring at least 1 note 3 and 1 note 4 when I travel for connecting to hotel TVs for media viewing(they have big SD cards). I have yet to use the headphone jack on my S8 active, only time I've used my phone with headphones was when flying, and I used my Note3/Note4 for that. I do not own any bluetooth headphones.
I'm sure most of the android fans will hate this post so expecting lots of down votes. I prefer freedom myself, if you WANT the latest you should be able to get it, if you DON'T want it, it should not be forced on you. I can't put into words how mad I was when my S8 active upgraded to Android 9 from 8. I went to great lengths to prevent OS upgrades. I successfully blocked my Note 3 from upgrading to Android 5 for 3-4+ years. The AT&T website even specifically said you have to be connected to wifi to get the upgrade. I was traveling at the time, not connected to wifi and it downloaded the upgrade anyway somehow.. On my home wifi I have AT&T and Samsung servers blocked at the DNS level so any attempts to upgrade will fail instantly.
Hoping this S8 active lasts as long as the Note 3 did(it still works fine now just a bit slow).