Sarah is an insanely underrated character. People think she's annoying, but I think peopele are missing the point of her character. She represents the people who are too weak to survive the apocalypse no matter how hard you try. People complain how even if though you can save her in one scene, she dies 40 minutes later. I think that's exactly the point! Her character is supposed to represent someone that no matter how hard you try, you can't save them. Something Jane mentioned, and why I think she's also an underrated character.
Spoilers for Return To Woodbury
In my opinion, Spencer-Lee is one of the stupidest and most boring novel villains there is. There is no point in his existance. All his character is, is an obsticle for Lilly and the group from moving back to Woodbury. If there was no Dryden in the picture, this novel could've focused on the rebuilding of Woodbury instead, and that would've actually made a great read. Kind of like in the novel, Descent.