For better or worse, which 7DTD update seemed most different from the version immediately preceding it?

Title, basically. I'm under the impression that A20 was a pretty big change from A19? I didn't play A19, so I can't say. I think A17 was also a big change from A16? I didn't play either of those, but that's based on what I've read.

So, from one version to the next, which version of 7DTD changed in the most noticeable way where the game seemed the most drastically different?