looking for post-apocyliptic/alie n invasion/action flicks

So I'm a big fan of above genres. I love seeing depictions of the world after civilization collapses and the human race is reduced to fighting for survival. My biggest problem is that I haven't found too many that were actually good, and not just some campy, cheesy 120 min headache with bad actors/actresses and even worse writing. So, I'm looking for suggestions that you think would fit my criteria.

Stuff like Falling Skies (TV, I know), War Of The Worlds (if it was actually done right), Battle: LA (again, if it was actually a good movie), Black Hawk Down (if it was aliens instead of poor, brown people...USA! USA!) etc. As you can see, I'm having a hard time thinking of a quality example, so any suggestions would be greatly appreciated.



"Have you a valediction, boyo?"