I have T420 (and T430s) as well, but I think at this point it no longer qualifies as a daily driver. Even with 16GB of RAM there are times when the machine is just slow. Even with a replacement battery I only really get a couple of hours. Performance is just not there for anything serious. I've used linux and BSD's on it for about 5 years. It's true you can repair it fairly easily, but after getting my hands on a refurbished M1 MBA, there is a huge difference in quality, performance, battery life, etc.