Tracy M. Shadows by Paula Weston! It's about the children of the Fallen Watchers. It's giving me the Angelfall vibes!
Loes Fallen series by Lauren Kate or Hush Hush series by Becca Fitzpatrick maybe? Both about fallen angels
Traci Smith right now I'm reading the blood of eden series, it's not angels but vampires. it's got that whole post apocalyptic vibe going on. and there are definitely certain qualities to the story that are similar to angelfall.