what are the advantages and disadvantages of each version of Eclipse (Juno and Kepler) ? which one is the more stable version ? how to choose the right version of eclipse?
Each eclipse release has some bug fixes, new features updated APIs etc.
You can check News and Noteworthy section of each release to know how the current release is different from its preceded version. Kepler News and Noteworthy section is here.
Compare the each feature/involving projects version of both Juno and Kepler from here and here.
Note that Kepler feature versions are higher(or newer) which indicate the bug fixes or new feature in new eclipse version.
For detailed difference check all the bugs or issues assigned to newer versions of each features in eclipse bugzilla
Good News. Now its easy to see issues addressed in a given eclipse release. Here you can find the all eclipse released versions till now here: https://projects.eclipse.org/projects/eclipse/governance.
To view issues addressed in a given eclipse release. Use this link http://projects.eclipse.org/projects/eclipse/releases/<EclipseReleaseNumber>/bugs
Replace <EclipseReleaseNumber> with the required eclipse version.