Exponent has been really easy to use for me to get up and running and I'm using it more and more. Pretty much gets all of the tooling out of the way, i.e. xcode and android configuration, and let's you start building real React Native apps quickly. They've been doing a great job of improving the platform, and from what I understand by reading this you can now even easily publish the apps to the app store which is a feature they did not have when they first came out with Exponent if I remember correctly.