Smartphone Buying Guide

A Better OS ensures smooth performance making the phone easy to use. Popular Operating System are Android, iOS, Windows.

Android being the popular one. Stock Android from Google provides the best performance, Most smart phone makers customize the OS adding a interface layer known as Custom Android versions, allowing features which were not available on Android, it sometimes lead to unwanted preinstalled apps. Android Go is a lean version of Android meant for budget phones while Android One ensures latest innovations giving the best possible AI experience.

Battery capacity is measured in mAh, higher number indicates higher capacity. How long the battery lasts also depend on the screen size, power efficiency of the processor and usage, depending on apps running in background. Batteries may have Fast Charging or Wireless Charging. Now-a-days Phone comes with non-removable batteries, which gives a compact slim design.

A smart phone with good display creates immersive viewing experience. Screen size is measured diagonally usually in inches. Larger the size better the viewing experience. Larger screen consume more power and is cumbersome to some users. While, bigger screen have benefits it adds to size and weight. Manufacturers have found a solution by bringing Bezel-less displays by narrowing the border between the screen and the frame of the phone.
Aspect ratio is the ratio of height to width of the phone. Phones with higher aspect ratio are called infinity displays.
The Panel Type can be IPS offering good displays or OLED offering vibrant colors and better battery life.
Higher Resolution has more pixels on screen delivering higher clarity and sharpness, but consumes more battery power.
Screen Protection like Gorilla Glass protects the screen from scratches and damages to some extent, higher the number next to it the better it is.
A few phones come with Dust and Water Resistance providing sufficient protection from rain.

While deciding the camera, we need to consider the Resolution in Mega-pixels, The Lens and Optics make.
The Aperture size which is the opening of the lens which lets light come to fall on the sensor.
The Focus method which is usually indicated as Dual Pixel Auto Focus or Phase Detect Auto Focus.
Optical Image Stabilization and Electronic Image Stabilization produce blur free images despite of little shaking while clicking the photograph.
New Phones comes with multiple cameras which may include depth sensor for Bokeh effect, telephoto lens for zooming, wide-angle lens etc.

The factors to consider are the Processor and Memory. Qualcomm snapdragon processors are common, while other options are Samsung exynos, Apple Bionic, MediaTek Helio, Huawei Kirin and more.
One needs to consider the Series, higher series is better than lower series SoC.
Clock Speed and the number of cores determine the processor performance. The Semiconductor device fabrication is shown in nanometer, smaller values are new and is better, Today we have 14nm, 10nm SoC available. By end of 2018, mass production of 7 nm devices has begun.
The GPU processes graphics and impacts on video performance which need to be considered.
More RAM provide room for running apps to reside in memory, typically 4GB/6GB of DDR3L/DDR4 RAM is considered sufficient.

The other factors depending on your budget and requirements to consider are:
Dual SIM v/s Hybrid SIM,
Network Connectivity and WiFi,
Security features including Biometrics authentication,
Design and Ergonomics, and Sensors which might include Accelerometer, Barometer, Fingerprint Sensor, Gyroscope Sensor, Geomagnetic Sensor, Hall Sensor, Light Sensor, Proximity Sensor etc.