The commenter above is correct in that I don't like plastic as the primary reason why a Thinkpad is out... Perhaps if they produced an aluminum unit I'd give it a shot.
I really want to emphasize I'm talking about my preference. I don't want to anyway say that the Thinkpad isn't great for some folks.
With that said...
I personally just don't like Thinkpad keyboards at all.
A MacBook Pro (MBP) keyboard for me is much nicer to type on, but it's also completely inferior to a mechanical keyboard (again, for me).
I've looked (online) at some from HP (envy?) and they seemed alright but were often underpowered for my tastes. I really like that I can get a high power i7 in a MBP. Cheap? No. Fast? Yes. I'm okay with paying that premium.
I haven't tried the Lenovo Thinkpads; so, I am admittedly behind the times.
One change to MBPs that I loathe is not being able to upgrade my ram or SSD. I'd be fine if it was a weird format/connector/size, as a result of the form factor, but having them soldered on is a step too far.
I also very much miss my matte screen. Matte "stickers" (?) suck and just look shitty.