For a compact powerful mirrorless camera, look at the Olympus E-M10 MkII (its successor might be out later this year) or the Pen-F. They can be used pretty much

For a compact powerful mirrorless camera, look at the Olympus E-M10 MkII (its successor might be out later this year) or the Pen-F. They can be used pretty much one handed, and their body isn't much larger than an mobile phone (though thicker, and of course much more so with a lens attached).