Pro Uses the powerful Gradle build tool out of the box
Android Studio uses Gradle as the official build tool for projects, moving away from the now outdated Apache Ant.
Gradle is a powerful build tool, especially for Android development with which it's very easy to do things that are otherwise impossible or very hard to do on other build systems, thing like: upgrading the build system without breaking the project itself or allowing you to separately define the development and production versions.
Pro Extremely fast preview
Since Android 2.0, Google have been focusing more and more on the IDE's speed, going so far as making it 2-2.5 times faster than older versions.
But the greatest feature when it comes to speed though is the new feature called "Instant Run". This is comparable to writing HTML, where you write the HTML and just refresh te page to see the changes. On mobile though, updating anything would take a lot of time for the system to rebuild.
Instant Run allows developers to build their app once (on physical devices, emulator or both) and as they change their code, AS does hot code swapping where it only updates the parts of the code that have been changed and the developer can see those changes after a second or two.
Pro Officially supported by Google
Android Studio is the software built by Google themselves to be used for Android Development. As such, it's certain that support for it will never drop as long as Android apps are still being developed.
Studio is also the tool that Google recommends using for Android development and it's the IDE that gets updates related to Android first.