I began studying Android development 3 weeks ago first with Eclipse because I have prior experience with it because of college, but every modern lib I try to add mentions Android Studio and Gradle and it seems like it could be better if I used both.
What are the pros e cons of Android Studio and Eclipse?
So using a library designed for Gradle is going to be a pain in the ass with Eclipse. Additionally, the Android Tools team has chosen to focus on AS for various reasons in order to provide an IDE really dedicated to Android.
The choice between Eclipse or Intellij (Android Studio is based on IntelliJ) can be difficult for general Java coding, but in the context of Android, even though AS is not perfect, it is the best solution at the moment.
Unless you are writing NDK code (c++), in that case support is way better in Eclipse.