Usually the right answer is the most recent production release compatible with your installation (although normally, upgrading PHP should not be a major headache). Since APC suppport is dropped from PHP v5.5 onwards, the most recent version of APC (3.1.3) will be the right one to go for. The PECL site lists the builds compatible with your current setup.
(NB upgrading to 5.5 is a bigger jump than previous minor number upgrades due to the change to Zend opcode+optimizer)