I use the ToughBook series extensively. My work with the US Army Engineer Research and Development Center makes use of the ToughBooks in various configurations for military applications. I used ToughBooks when deployed in Iraq. They are reliable and forgiving of "oops" situations if a bit short of memory and storage capacity in "stock" form. Buying a used one certainly offers the opportunity for upgrade for a substantial reduction in investment. I don't personally know of a more rugged laptop computer which has been "real world" (i.e., my world - military battlefield demands) tested.
Jonathan