JDeveloper more or less pushes you to use ADF Mobile (or whatever the current name is) which is Oracle's own development platform for mobile devices, which generates executable packages for both iOS and Android from the same source.
Eclipse will get you the raw Android SDK (and possibly not the latest, given that Google made a deal with Jetbrains and switched to distributing a customised version of IntelliJ Community Edition instead as the prefered IDE for Android development a year or so ago).
Different flavours, different target audiences. Try both, read the license terms carefully. ADF Mobile for example might require you to buy something from Oracle if you want to distribute the generated packages (not sure, but do check).