New Joomla versions are continuously released – Joomla 2.5, Joomla 3.0 and so on. Joomla 1.5 is no longer supported anymore. That is, I guess that some Joomla 1.5 users might wonder which the next version you should stick to. That should be a version with new useful features, long-term support and a lot of compatible Joomla templates and extensions.
Our answer is Joomla 2.5. You know, it is still supported until December 2013. It is not Joomla 3.0 which is just supported until April, 2013. More reasons? Please take a look at the infographic below: