The most recent release of the Einstein Toolkit is ET_2016_11, code named "Payne-Gaposchkin". We expect this version to remain unchanged, save for correcting serious problems that may be detected. This version should be your first choice if you are new to the Einstein Toolkit, or if you want to perform production simulations.
In addition to the releases, we also have a development version where (unsurprisingly) most of the development occurs. Our gentlemen's agreement is that the development version should build and run correctly on most of the important platforms at all times, but this may not be the case on a bad day.
List of Einstein Toolkit releases: