Quite probably the most durable reliable upgradeable & easily repairable is a CLEVO D9F. it's quite old now but it's solid and capable. It can take up to 24GB ram, Nvidea GTX 480 M, and an Intel i7-990X 3.46Ghz six-core desktop CPU. Once the fastest laptop in the world. Of course 8 years on that's no longer true but surprisingly it's still amongst the quickest laptops. A pretty amazing machine. I would not take any persuasion to buy another!
Toughbooks is just a product name. You can discount that product. If you want something serviceable that can still be going in five years despite being six to seven years old already you can't do much better than the CLEVO D9F/D900F, to which I already alluded above.
It does depend on how it is to be used. Ruggedized laptops like Toughbook or Getac are given to soldiers who may drop them from 10' high, and even children to play Barney games on in the pool.
If you wanted something with easily replaceable parts, I don't think HP, Lenovo or Dell are bad at all because they make them by the millions so you will always be able to easily find parts for them. For a white-box OEM like Clevo, the parts may be available but under many other brandnames and part numbers so it's trickier, especially used parts. But at least they, like Asus, Acer, and MSI, don’t whitelist.
Note the text from Pelican lifetime warranty:
This guarantee is void only if the Pelican™ product has been abused beyond normal and sensible wear and tear. The guarantee does not cover shark bite, bear attack and children under five.