I've just wrote one, but I'm still getting it ready for an agent.
What do I like? 'Alas Babylon' wasn't bad by Pat Frank. I loved 'The Mist' by Stephen King, and 'The Stand' of course. I read the McCammon book Swan Song, not bad. Lucifer's Hammer was good. I've almost picked up that 'Canticle' book several times, but could never convince myself. I will now.
Welsh if you can think of more please post them. I haven't read anything good in this genre for a while.
I haven't heard of Blood Crazy or Metal Fatigue, but I'll check them out.