Foxy > Chica > Freddy > Bonnie

[thejaker]

In terms of scariness I say. Foxy never stops being ♥♥♥♥ scary, the way he stares out of pirate cove at you and when he charges you down the corridor, it's full on heart attack fuel.

[Foster Kia]

Actually, I'm pretty sure it's like this.
Freddy > Foxy > Bonnie > Chica

Now, you may be asking why.
Well, in terms of creepiness, Freddy probably takes the cake. Let's not start on that nightmare fuel out of power jingle. The reason Freddy's so creepy (in my opinion) is because he seriously WATCHES you for the first 2 nights. 3rd night? Freddy exploits every single one of the flaws.
Just so he can scream in your face at the sound level of a meteor impact.
Another creepy thing about Freddy is that... he just loves to give you a death-stare through the cams.