I have a T420. A few years ago I switched to a slightly used T480, keyboard was a huge downgrade and the whole series can get really stupid USBC issues. After half a year or so it didn't dock anymore and I got an X1, basically the same laptop glad I found it without touch and the 'bright screen' because the screen is barely good enough, keyboard is the same and USBc already started to get finicky.

Meanwhile my T420 still runs like on day one (which was already 5 years old when I got it, and travelled 1+ years with me in a backpack), the screen works in direct sunlight and it's not even the best of its series, hardware still perfect. Fat SSD + 32GB Ram and you can barely tell how old it is.