What should I read next that has to do with Armageddon?

If you want to try something less "fantastic" and more reality-based in content than the books you mentioned, you might want to try "Into the Forest" by Jean Hegland. It's a dark, beautiful, disturbing book. That's not to say that I didn't enjoy the books on your list. Some of them are quite good. "Into the Forest" is just different.