Another good one is 'Gurren Lagann'. Although it has a different art style, it shares the element of a group of characters fighting against great odds. In 'Gurren Lagann', the characters start from the bottom and gradually rise to take on powerful enemies, similar to how the Night Raid in 'Akame ga Kill' fights against the powerful and corrupt empire.
One anime similar to 'Akame ga Kill' is 'Claymore'. It also has a dark and gritty atmosphere with female warriors. The story is set in a world filled with dangerous creatures and the Claymores, half - human, half - monster warriors, fight against these threats, much like the assassins in 'Akame ga Kill' battle the corrupt in their world.