Which eclipse version best supports Salesforce? Helios? Kepler? or Juno? which one to prefer
The easiest way to find out which version is supported is to check it on the Force.com Plugin page:
Prerequisites (for the 26 August 2014)
Java SE Development Kit (JDK), Runtime Environment 7 —the plug-in will fail to load if you don't have the full Java 7 JDK (note: the full JDK is not the default JRE installation on Mac OS X)
Eclipse Juno (4.2) or Eclipse Kepler (4.3) — the 'Eclipse IDE for Java Developers' distribution is strongly recommended
Juno works fine for me. Although I prefer Sublime Text with MavensMate.