You cannot lose with either of the Lenovo laptops as unlike the others on your list they just work. Now the C930 is a consumer laptops while the X1 is an enterprise one, and enterprise laptops from any OEM are just more robust than their consumer cousins are. I have owned laptops from all three that you mention and Dells are subject to both system-board and battery failures rather quickly - first year or 1 1/2 years. The HPs will suffer form display and system-board failure. Lenovo is the best choice as I said in the beginning they just work, are more robust, have a superior charging system so you do not have to worry about replacing a degrading battery after a year or two.