What's wrong with modern Thinkpads? They have every base covered,
workstation to thin and light. Linux support is decent. Still come
with full service manuals etc.

NEC make good laptops too.

They aren't as easily serviceable as older Thinkpads. For instance, 
replacing the battery now requires you to open up the back cover and 
unplug a fragile ribbon cable, while with older Thinkpads (like the 
X200), you can simply slide a new one in. Pretty useful when you want to 
swap in battery on the go and you have a spare in your bag.

In some cases you can even replace the CPU and RAM (like on the T440P 
which I currently use). If I wanted to, I could upgrade to a quad core 
to get additional performance in many workstation tasks without getting 
a new laptop entirely.