Smart Phones How to know which one is right for you. The latest Android operating system, Android 6.0 Marshmallow, has begun shipping on Google’s Nexus devices. It should begin arriving on other makers’ handsets soon, too. Samsung Galaxy S6 The Sharpest Shooter As we make ever fewer phone calls on our smartphones, the importance of things like cellular antennas go down. But we’re taking more digital photos than ever, so all the camera bits, from lenses to image sensors, matter much more. Proving megapixels aren’t everything, the Samsung Galaxy has a relatively unimpressive-sounding 16 megapixel rear-facing camera. But it’s optics that matter most, and this quick shooter can snap off a pic in under a second, simply by double-tapping on the home button to pull up the camera. A motion tracking auto-focus feature helps photographers lock in on moving targets. But the real magic inside this shooter is a larger aperture that lets in 34% more light, an improvement ...