Laptop when I'm at my desk, but otherwise I actually use my smartphone. It's a biggish one, and in landscape orientation it's enough to fit the (printed area of

Laptop when I'm at my desk, but otherwise I actually use my smartphone. It's a biggish one, and in landscape orientation it's enough to fit the (printed area of) the width of a pdf page in a decent font size. The convenience of just taking the phone out of my pocket and start reading more than compensates for not having a whole page in view.