Knights of Sidonia

After the bleak abstraction of Blame!, Tsutomu Nihei wrote something with an actual cast and a plot you can follow. Knights of Sidonia is set on a seed ship carrying the remnants of humanity through space, a thousand years after a shapeshifting alien species called the Gauna destroyed Earth. A boy named Nagate, raised in hiding in the ship's underbelly, surfaces and becomes a mecha pilot defending the colony. There is mecha combat, a tangled love triangle, and a society of cloned and gene-modified humans living in a closed metal world. It is more accessible than Nihei's earlier work without losing his eye for enormous, lonely industrial space.