My refurbished Xperia X died after less than 3 years so I’m looking for a new phone. I got the refurb in early-mid 2018:
In 2018 I had to replace the camera module
In 2019 I had to replace the USB port
In 2020 the phone just straight-up died.
If I stick with a Sailfish X device should I keep expecting my phone to die every 3 years or did they improve build quality with the XA2 and later models?
Build quality of Sailfish compatible Xperia phones is declining, not improving: X > XA2 > 10.
However, this is not really a fair comparison due to their differing price ranges.
The x came at a launch price of 550$, while xa2 cost only 350$ at launch, just like the x10.
So you couldn’t expect anything else…
That is strange, I run X which I’ve bought in 2016. I did change the battery but otherwise there are no issues with the device.
Last year I’ve purchased 10 Plus, which is already good for refurbish as touchscreen died. It is likely my last Sony.
My opinion is that Sony build quality is very good compared with other vendors. My Xperia X had its USB connector burnt due to a defective cable but was almost new after 2 years usage. Opening the device, I found that the connector was screwed to the case and connected with a flat ribbon cable, and it was a charm to replace, unlike most other brands which simply solder the connector to the motherboard. My current XA2 plus is still in mint condition (always kept with clear sleeve and protection glass).
I also have an XA2+ currently and taking good care of it. But the Xperia X definitely felt more of a premium device (also more expensive at launch). I had the 10 in my hand too, and that is even more like “cheap plastic” compared to the XA2+. I just commented my impressions. Luckily my USB connector has not died yet. 
I definitely will give points for repairability. Both of my fixes were easy, but the dying randomly hasn’t instilled much confidence in the phones for me 
I like Xperia 10. It reminds me my old Lumia 820.
I had issues with the camera on a brand new Xperia X and Sony refused to fix it (of course). Best to buy refurbished or second hand IMO.
I only buy second-hand phones and for that Sony devices have not disappointed me. Nice price and build quality is decent.
Sony builds nothing, Foxconn does, so they are to blame. All the x label’s build quality is better than y’s is pointless imho. It’s just badge engineering mostly.
My XA2+ is the most sturdy phone I have had sofar. It fell several times, yet it is still fine. I use a good case.
My former phone was an Xperia X. The sides were of a painted plastic, not real alu. The back was alu, that is more durable than plastic, but overall the XA2 is better quality than the X.
I wished we could buy a phone with changeable parts.
forget it. Also the times of a full aluminium body is over, they were too sturdy. All new phones are built like newer iphones with even glass on the back for planned obsolescence. Even a fall from some cm will crush 'em, happend often with my Mi 8 which has almost the same body as the iphone x. Xiaomis Mi line and iphones are even produced on the same assembly line at Foxconn. Well, all phones being almost the same saves Foxconn a lot of money.
Anyone had a Nokia Lumia 920 WinPhone? I even opened beer bottles with it, it was uncrushable.
I wish I could buy a decent phone with a chassis made in 100% polycarbonate, rather than enclosing antennas in an electromagnetic metal shield, or in glass which is known to shatter when dropped.
Polycarbonate is nice but not the last answer when it comes to durability.
A lot of N9s suffered from cracks at the USB door plate and/or SIM card door.
Mine had some small cracks after (only 
) a few years usage. And I had to tape my SIM card holder and eventually glue it.
So 2011 to 2018 and now the body at the top is fully cracked (never dropped, always treated like a baby).
A Fairphone perhaps?
Polycarbonate means a lot of things. It could also be PMMA with BisGMA like composite tooth fillings or PEEK. That would definately last.
Sorry, no chemical analysis done on pieces of my broken N9. So it may be any arrangement of elements and chains 
Anyone out there that knows?
And yes there may be hundreds / thousands of possible ‘plastics’ but you need to find the right one. It must be hard, endurable, flexible, soft, good haptic and so on…
The one from N9 was quite good and it lasted around 5y for me. Not too bad but I am still a bit ‘disappointed’