Well if you want to be a control freak (like me) I have all of my settings (in shields with multiple actions) set to Ask as the primary action and Secondary set to No Action, that kills the third option. That said the avast defaults aren't bad as generally they are trying to prevent this and it also has protection against the deletion of system files, but generally that is for those with a digital signature.
Other shields that may have only Auto I set to Ask (AutoSandbox, Behavior Shield). I don't use IM or P2P so they aren't installed on my installation of avast.
There are some that would advocate Repair as a first option, Move to chest as a secondary and No Action as the third. You may have noticed I don't like delete, that is final and you have no actions left, the 'first do no harm' is one you should follow and investigate rather than delete.