Hi Spider, I played State of Decay on the Xbox 360 when it came out. Totally different game then 7DTD, but of course that's what you are looking for. Not sure what they did with PC version. There is the same "searching" for stuff to "use" element, which is more tense in that game I felt. Some of the "missions" are tad tiresome and if you don't complete some of them you can feel like you "failed" part of the game. The NPC's are fine. There are good and bad points that you'll find. For the most part you will want to try and keep most of them alive (which is another game element). Story is meh, but it is not the selling point. Map is pretty huge. No real "crafting", but you will "build" and "develop" things.
It was the first "real" zombie game I played and I enjoyed it a lot. I know there is also download content that extends the game and focuses more on being able to "survive" for an amount of time.
It is different enough that I think you would enjoy it, while retaining that "living in a changed zombie infested world" feeling.
I may still venture into "The Forest" at some point. Have some Steam cards to spend. Waiting a few more weeks to see how much further they get with it. Been watching people play it on Twitch.
I always recommend people try to find others playing the game they are interested in on Twitch and watch some game play. You can run the risk of "spoilers" but not so much in these types of games.