Books

For grimdark I recommend The First Law trilogy. It's a little like Lord of the Rings mixed with Game of Thrones. You won't find too many fantasy creatures or instances of grand magical displays, but the few you do will be pretty memorable. The characters are all terrible people and I love it that way.

An honorable mention is The Warded Man which has a world overrun with demons that hunt in the night. The only protection humans have is some settlement walls painted with special wards that help keep them away.

For an interesting magic system check out The Lightbringer series. It's based off color, with each one having a unique property and psychological effect on the user (e.g. red light creates flammable materials and makes the user get a little enraged). It features technology made from the materials made out of this light and even has a church that governs these magic users.