Every Call of Duty zombies game ranked (tier list)

Today we have a slightly different video.
I have created a tier list of all Call of Duty zombies games and I have ranked them from worst to best! (Extinction from Ghosts does not count!)
Let me know what you think to my list in the comments and what you would change, I'm always open to discussion.
REMEMBER... This is purely my opinion, everyone is entitled to their own opinion so be mindful and respectful of other people's in the comments.