The universal cell phone mount will give you the ability to activate a function of your device and use whatever features are allowed by law, which if you are in Washington State is very limited. This is a good option for people who would like to follow the phone's built-in GPS or activate other essential device features.
A Bluetooth hands-free car kit is an excellent choice for connecting your wireless device to your factory stereo. This will allow you to make and receive phone calls, and in many cases streaming audio for music. Be careful though; some of these Bluetooth units may require that you control these features through your phone.
Depending on your particular needs Apple CarPlay or Android Auto aftermarket receivers might be the best option for you. If you are looking to add a mix of great features and safety, you should consider one of these units. CarPlay-enabled receivers, through Siri, allow you to control many of the features of your Apple iPhone such as music, maps, messaging, and phone calls. Similarly, Android Auto has a very robust voice-command feature powered by Google. Just say “OK Google” or press and hold the voice command button on your steering wheel, or touch-screen interface to activate voice commands. Just like CarPlay-enabled receivers you can make and receive phone calls, access your messages, get turn-by-turn directions, and much more!