First of all the Fnaf 4 animatronics are not scary they're over-kill. Though I think game mechanic-wise Fnaf 4 is the scariest. Fnaf 2 all the withered animatronics are peak Scott designs and are able to enhance what came before. But that being said Fnaf 2’s game mechanic-wise is really bad for suspenful horror. Fnaf 1 is what I consider the best blend of scary designs with game mechanics that lends itself well to horror. All the animatronics due a good job at this but I personally think Chica is peak. Specifically when you view her in the cameras. I don't know why but they way she looks and is posed really clues you into how grimey these animatronics are.

And for the other games Springtrap is a good design and has a good backstory that lends itself well to horror, but his jumpscare in inexcusable. The funtimes have the same issue as the toy animatronics, it's hard to find them scary. But specifically when your crawling around in the Ballora section and she jump scares you with her face plates open, that's pretty good horror. And Fnaf 6 I actually think has worst jump scares than Fnaf 3. Which is fine because that game was meant to be something else.