Price, keyboard and build quaility are my main reasons for buying a Thinkpad 3 years ago.
They are available for a good price second hand and their keyboard is the best laptop keyboard I’ve tried. Most of those Linux manufacturers use Clevo designs and thus the keyboard isn’t amazing. Even if they design a laptop themselves it’s difficult to nail the keayboard.
My next laptop will probably be from framework. But that depends whether I’m willing too spend as much and the other options available. And framework doesn’t even sell laptops with Linux preinstalled.