I have an Atoto A6 which I got on sale for around 200. I love having android in there but I should have forked over closer to 300. I have several issues with it but some recommendations I would make are to have physical buttons as full touch screen is difficult when driving. Find out if your device can be rooted ahead of time. The model I have turns on the radio every time the car turns back on. And unless I figure it out myself (which I'm not smart enough to do) I would need root access to change some settings. You need a minimum of 2 gb of ram. Also make sure your unit will fit. The A6 was marked as a 2 dim but it was off on the vinyl behind the faceplate so I had to either get a new vinyl panel*yea ok* or cut away at an area which wont be seen. You might want to think about getting a sim card as well since even though waze will work offline, you wont be able to do much else without net. You can miracast some things but its more of a pain to have to set up every time you want to use it.
All of that aside. I have dual bluetooth in the HU which is awesome as I'll bluetooth my phone to work with the HU so Youtube's audio or Spotify's music still comes through my speakers and I can play/Skip via the Bluetooth controls menu. The 2nd bluetooth receiver is awesome as it allows me to leave an OBD2 sensor in the car and get real time readings and Fault Codes from the Torque app.
In the end you get what you paid for, not always what is advertised so dont be afraid to put a little more money into it. It'll save you a lot more time and stress in the end.