When it comes to Android TV units there are a handful of choices for standalone Android TV boxes, NVIDIA's SHIELD Android TV is arguably the best though for more than a few reasons. Not only does it support 4K video, but it also has a really powerful processor and graphics processor inside of it which allows it to perform extremely well fr multitasking and for playing games. In fact, one of the defining features and a major benefit for the NVIDIA SHIELD is that it was designed to be a gaming-focused Android TV unit, and it does things well.
The NVIDIA SHIELD is perfect for gamers in fact. With the NVIDIA Tegra X1 inside it's equipped to handle all kinds of AAA console-quality games through the GeForce NOW streaming service. If you subscribe to it monthly then you'll get an ever-growing list of game titles which you can stream and play right on the console without having to download and install them to the machine. In addition to those, some console games are being ported to Android as NVIDIA SHIELD exclusives, like Borderlands The Pre Sequel or more recently Metal Gear Solid 3 HD.
Beyond games, the NVIDIA SHIELD is also on Nougat for the Android version software that it's based on, and it supports Google Assistant so that you can ask Google questions or request it to complete a task such as turning on or off the lights and/or adjusting the temperature of the climate in your home via a smart thermostat. Since the NVIDIA SHIELD runs on Android TV that means you have access to the Play Store which means access to tons of different applications such as YouTube, Google Play Music, Spotify, Pandora and more, and if you're big on streaming your movies and TV shows then you'll also have access to services like Hulu, Netflix, HBO NOW and HBO Go, as well as many others. The NVIDIA SHIELD does come with a remote for navigating content, and this has a mic button if you want to use Google Assistant, but it's also possible to navigate content on the device using the SHIELD controller, which you should have if you plan to play games on this device.