The right action of course. I mean, wouldn't you be more concerned with the results? (and logicaly if it's the "right action" then the results must also be the right ones. Like, I foil a secret plan to destroy the world because I don't want to die with it; that's the wrong reason to do it (being concerned about only me and noone else) but the action was the right one, and in the end everyone benefits from it (except whoever wanted to destroy it to begin with, but majority wins).
On the other hand if I do something bad for a good reason it might not turn out to be fine in the end. I mean, we can argue what a "right reason". For example, brutaly murdering a another male could be a good reason, mother nature says so. But since we are smarter than that (or are we? :p) we see murder as a bad thing, so then we could say it wasn't a good reason to begin with.
But then, I'm thinking... how can we know what a "right action" is? Nothing is true or false anymore, AHAAARGH....
You know what? I probably misunderstood you question anyway :p
There can not be Good without Evil, so then it must be good to be Evil sometimes.