Not my favourite necessarily, but I've recently finished the Last Policeman trilogy and loved it. The premise sounded a bit
, but it was actually really good - the slow unravelling of society as the trilogy progressed was gripping, and very convincing.
There also used to be a lot of kids'books about nuclear war around in the 80s, remember them? I must have read Z For Zacharia and Brother in the Land 20 Times each.