Man, i love me some Thinkpad laptops!
For me, its the overall sturdiness, the historic ability to more easily swap out components, and the keys and keyboard combo. I haven't had so many Thinkpads as others have had, but of the few i have owned, i think so far the T420 from i think circa 2011 (?) seemed to have the best balance of sturdy boxy goodness and wonderful keys and keyboard. While i would not say that i am a keyboard snob, i can certainly appreciate differences between the different types of keyboards like chiclets, or mechanical dedicated keyboards, etc. I'm sure beyond functional aspects, there is no doubt a nostalgia that i feel for these machines that is solely based on emotion...but who cares, since i always get more value than whatever i paid for them!
On another aspect to this, it feels like Framework laptops has a chance to perhaps capture at least some of the positive sentiment that folks have/had for Thinkpads. I mean, sure, the swap-ability of the components is the most obvious comparison...but, i think Framework has also fostered a following by a community, that, if they play their cards right - and produce good, solid products - can turn into a successor to Thinkpads. I mean, obviously thinkpads are still here and all...but the folks at Framework have a big chance here, and i welcome the competition (since we all win as consumer if there is good, solid choices in the marketplace). Let's hope both Thinkpads and Framework (and any other competitors) keep moving the needle forward to empower users with more options for good solid design, easy/self-repair, component swap-ability, sturdy/dependable hardware, and fair pricing!