I've had my hands on Fairphones and SHIFT phones. Build quality seems similar.
I'd still get a Fairphone, as they put a lot of effort into open source and being part of the community. They also seem to make slightly more robust devices.
No idea for how long Shift guarantee updates, but Fairphone guarantees updates for many years. Last I checked it was eight years.
BTW, I recently got myself a USB-C charger from Fairphone and the build quality is really good. No doubt it will still work in two years and longer. The price is also decent.