Yii uses the 1st but most of the frameworks out there (sf, zend, java-struts) uses the 2nd style,… akelos, Codeigniter and cakePHP do not use the action word at all (3er style)
IMHO name+Controller and name+Action seems to be more intuitive…
I prefer indexAction just because is easy search method. If you use netbeans, u can press "Ctrl+7". This shortcut open the navigator of the class. And u can type action name. And get the right method. Press enter, and focus it.