This one is not actually an emulator it a android OS but you can install this as a partition on your computer and boot up the running native Android.
It is not great for consumer use but does offer services for free for personal use.
You can also switch between virtual devices easily. It is mostly for developers and lets you test your apps on various devices.
With Bluestacks also you can play multiple games at the same time, record it and replay any action in real-time. However, it also has various features for best use. Bluestacks includes key-mapping and settings for many games that provide a better experience and is easier. It was also one of the first that worked really well and gets regular updates. This is the most popular of all emulators as it is compatible with both Windows and Mac.