This is a loaded question, the short answer is it depends. The question should be “What is the best Sony Mirrorless camera for me?” What do you want to use the camera for would be one of the first questions I would ask when some one ask me this question. Do you need a high end high resolution professional camera? Do you plan to mainly take photos of your kids sports and family stuff? Do you do need to take video? Do you blog? What is your budget? While technically the top end Sony A7R III, A7R IV that just came out or the A9 are the "best" Sony mirrorless cameras out there are they over kill for what you need.
Here is some back ground on a few of the Sony mirrorless cameras and the best uses for each model. Sony makes cameras for beginners, travel photographers, enthusiasts and professionals. They come in two main types: Sony Alpha mirrorless cameras which take interchangeable lenses, and Sony Cyber-Shot compact cameras with fixed lenses for all kinds of users and all kinds of budget. We’ll help you decide which type you need and which Sony cameras are the best (and the best value) right now.
Sony Alpha mirrorless cameras are designed for more advanced or enthusiastic photographers who need the versatility of interchangeable lenses and don’t mind a little extra size and weight. They’re the best choice for hobbyists and enthusiasts and pretty much the only choice for professionals.
Sony Cyber-shot cameras don’t take interchangeable lenses – but that doesn’t necessarily mean they’re limited. There are some simple point and shoot models in the range which make great low-cost family cameras, but there are also more advanced Cyber-shot cameras for keen photographers who need a powerful camera that fits in a pocket, or for sports fans and videographers who need a longer zoom range than they can get with an Alpha model.
Lets take a look at some of the top Sony Alpha cameras that are available with either APS-C or full-frame sensors. The APS-C models are smaller and more affordable and designed more like traditional rectangular ‘rangefinder’ cameras – but they still pack plenty of power. Sony’s full frame Alpha cameras are more like mini DSLRs, with a conventionally placed electronic viewfinder on the top. These are larger and more expensive and more orientated towards expert and professional users – though there are still bargains to be had for enthusiasts.
Although it’s now over four years old, the A6000 is still one of Sony’s best cameras. Moreover, it significantly undercuts the newer A6400 and A6500 models for price. Indeed, it’s currently little more than a third of the price of the A6500. With its APS-C format compact camera styling, and access to Sony’s range of interchangeable lenses, it’s a small body that packs a big punch. Resolution is good in every area, from the 24.3MP image sensor to the 1,440k-dot electronic viewfinder and 921k-dot tilting screen. It lacks the ability to record 4K movies but overall performance and image quality are very impressive, and it’s terrific value for money too and would make a good lower cost entry level video camera for bloggers.
The Sony A6400 is effectively Sony’s ‘middle’ A6000-series camera, fitting in above the A6000 and below the top-of-the-range A6500. But it’s newer than both, packs a super-fast, super-high-tech auto-focus system, and great 4K video capabilities. Its still image quality is very good, but really this camera’s strength is as a blogging/vlogging tool for single-handed content creation. Its 180-degree screen is the key here, flipping up and over to face you to help your framing, facial expressions and delivery as you present video pieces to camera.
It might not have the glamour of Sony’s top-flight A9 and ultra-high-resolution A7R III and IV bodies but the A7 III camera grabs most of the best bits from both pricier models and delivers them in a more affordable package for most users. It features include highly effective 696-point AF system and a 5-axis image stabilization system that promises 5EV of compensation.There’s a new 24.2MP back-illuminated image sensor, coupled with the latest generation of image processor, and the two deliver amazing tonal range and make super-high-ISO settings possible. Handling is excellent, with a design that combines easy access to important camera settings with a typically compact and lightweight Alpha build. For top performance at a sensible price, it’s the best Sony camera out there for the average user.
The Sony A7R III, there are 42.4 million reasons why this camera is so popular. The ultra-high megapixel count enables you to capture the finest detail and texture in images, which makes the A7R III excellent for everything from architectural and landscape shooting to high-end portraiture and fashion photography. Even the view through the electronic viewfinder is deliciously detailed, thanks to the camera having the same EVF as the range-topping A9. Indeed, some of the image sensor technology is taken from the A9 too.Highly effective 5-axis image stabilization helps you to retain ultimate sharpness in handheld shooting, and the camera is no slouch either, with fast-reacting auto-focus and a speedy 10fps maximum drive rate.
If ever there was a camera to prove that you can get professional-grade performance and image quality without the need for a reflex mirror, this is it. Sony’s flagship A9 has the same megapixel count as the A7 III, but it boasts a higher-resolution electronic viewfinder and tilting touchscreen, both of which are beauties. As well as being a fabulous all-rounder, the A9 is a properly sporty camera, its stacked sensor design enabling a blistering 20fps continuous drive rate, while a cavernous memory buffer can keep you going for up to 241 Raw shots. This camera costs twice the price of the (also excellent) A7 III, but for professionals it’s a no-brainer.
Last but not least is the new flagship 60 megapixel A7R IV. The Sony A7R IV is a slightly higher-resolution evolution of the A7R III, which makes it the world's highest-resolution consumer camera. It boast improved battery life up to 670 shots w/LCD, 10 FPS with a 68 frame buffer, 567 phase-detect AF points full-frame, real time Eye-AF for both people and animals, Dual UHS-II SD slots just to name a few.
So as you see there are several great options to choose from the Sony line up for the "what is the best mirrorless camera" out there.
We use the Sony A7R4 as our main camera and the A7R3 for video