Think of the easiness and cinema factor of the Storyteller system with the versatility of GURPS.
Its simple,fast but at the same time robust.
AH is essentially Mad Max the rpg* but its so open on the design end that you can make any world you like and just use the V6** system.
We are currently planning a Nuclear Winter era game(with a bit of underwater action also)
If you enjoy your Post apocalyptic share of games make this your default rule-set.
*=(and about time someone made something like that without all the surreal Tank girl stuff other companies fill their products with)
**=(cute name isn't it? ;] )