Windows/Mac/Linux: Google's Android Studio is out of beta, replacing Eclipse as the standard for Android application development. Aspiring Android app developers: Eclipse is still good to know, but start learning Android Studio 1.0 now.
Android Studio is an intuitive development platform that has access to Google's cloud services, code templates, and GitHub integration. It also has an extensive set of digital devices for all screen sizes, intelligent code editing and performance analysis. There are plenty of resources for learning the new IDE, starting with the Android Studio page and Team Treehouse's Android Development Track.