Best secondary computing device

Well first let us point out the obvious, this is all OPINION, yes that magical word that can found fueling all flame wars. OPINION. Best is subjective. Anywho, what, in your OPINION, is the best secondary computing device, there is a large selection of cheap computing devices on the market at the moment. For example Chromebook, tablets, netbooks, smartphones, and even a few android laptops. So what is the best low end secondary device?