Recently, I require to upgrade PHP version from 5.3.3 to higher. Can any one tell me which version of PHP I should upgrade for? Which one is more stable? PHP 5.4 or 5.5 or 5.6?
The latest stable version is PHP 5.6.11
According to the release history, 5.4 is only getting security updates and 5.5 will stop getting bug fixes in 10 months. So 5.6 is your best bet. Considering there are only minor syntax changes between these versions, you should go for the latest anyway.
The 5.3 to 5.4 gap may require some alterations in your code. And if your code works on 5.4, it will also work on 5.6, so just use the latest.