I’d get the lenovo m710q suggested by @extrowerk some time ago. Haven’t tried it myself but it’s small, smart, reasonably powerful, and cheap (second hand).
If you want a laptop I can cast another vote for the x220 or x230 thinkpads, but if you’re going to use one as a laptop rather than with an external monitor then make sure you get one with an IPS LCD because the TN panel is really terrible. Also, the x230 is preferable because it has USB3 while the x220 only has USB2 (unless you get the expensive and rarer i7 CPU model).