Should I launch a Joomla! 2.5 site or a 3.x site?
From Joomla! Documentation
Revision as of 18:52, 20 February 2013 by Unworthyslave
Launch a 2.5 site if you want the most stable that Joomla has to offer and/or possibly if you plan on using many extensions. Launch a 3.0 site if all the extensions that you plan to use are Joomla 3.0 compatible.