Well, here's something that would save cosplayers a lot of time and effort: Attack on Titan hoodies. Comfy for the chillier fall weather, but still stylish enough to make you feel like a badass who battles against monstrous Titans as part of the Survey Corps.
The design comes from Deviantartist prathik, who you may remember from their incredible Avatar hoodie designs. Unfortunately, these aren't available for sale (yet), but if they ever are, we'll keep you updated.
In the meantime, here's the original theme for Attack on Titan, because it's ALWAYS a good time to re-watch that: