My thought is that instead of deciding whether to be openly aggressive or passive-aggressive, you should focus on reducing, and ultimately eliminating, that aggressive response entirely.

One thing that's important about anger is whether or not it's rational. We often have an unstated belief that all anger is bad. If the anger is coming from someone mistreating you or undue stress in your environment, the feeling of anger is your brain trying to motivate you to act. If that's the case, then dealing with the source of the anger is my suggestion.

If the anger is irrational, such as when the source is no longer present or even when there's no identifiable source, just realizing that you're acting irrationally can help. That said, even irrational anger is your brain trying to motivate you to act to fix some problem.

So yeah, I guess I'm saying that if you see anger as a symptom rather than a problem unto itself, you might be able to assert more control over it.