Older models are sturdy (IBM ones are very robust but are also too old), probably better with replacement parts availability.
Two-battery models, like X230-X270 models (and others) can have a lot of battery power put into them. Mine has 72Wh external + 24Wh internal, and I can hotswap the external one, so if I want to I can buy a second 72Wh battery to style on everyone else.
Generally good Linux support, but do look specifically how well whatever you are buying is supported.
edit: the models I mentioned don't seem to have magnesium alloy chassis, so while they might look like a close range weapon, you probably shouldn't use them that way.