Keyboards after the x220 are chiclet, which is sacrilege to most ThinkPad users (me included). x240 really messed up the mouse buttons that you'd use with the TrackPoint: they're touch instead of click and poorly executed. x250 and x260 fix that problem more or less, and the keyboard on the x260 is appreciably better than the x240, but it's still chiclet.

The main draw of the ThinkPad is that it's an unparalleled input system (TrackPoint means never leaving the home row, keyboards are second to none), they're very tough, have great battery life, very serviceable, and you can get amazing deals on eBay or through outlet/refurbishing. If you go with the X series, they're also the only < 13" machines that have replaceable batteries, a full complement of ports, reasonable specs, etc. In other words, they're the perfect dev machine. The cons are pretty bad screens, thickness, and relatively poor trackpads.

X220, X230 are made by Lenovo.