I feel you. I kinda end up with everything after the prison going downhill for me, in terms of both overall quality and zombie action.

There's a few episodes with zombie centric plots after that, and plenty of good scenes, but as a zombie show it gets weak during the prison season.

That being said, there's one of the seasons in or around Alexandria where there's an episode with a massive hoard being managed, and it all goes wrong, and it is a great episode, I just can't remember exactly when it was to recommend it by season/episode.