If you're looking for manga similar to Mobile Suit Gundam SEED Destiny: The Edge, you might like these titles.
The human race has one year left to live. Aliens known as the Gamilas have attacked Earth, poisoning it with radioactivity and driving humans underground. As humankind grows sicker by the day, their final hope is the space battleship Yamato–constructed from secret plans and equipped with advanced technology. Its mission: to reach a distant planet and bring back a cure to save humanity. Will the ship and its crew rescue the Earth in time?
World War Three is over, but for nomad soldier Deunan Knute and her cyborg lover, Briareos, the greatest challenge lies ahead, not in the abandoned cities and DMZs of a post-war battlefield, but on the streets of a new "utopia." Shirow Masamune's visionary Appleseed is widely regarded not only as one of the linchpin works of graphic fiction, but one of the most influential science-fiction stories in recent memory, culminating in the astonishing 2005 animated adaptation. Appleseed Hypernotes, never before collected in America, features an over 80-plus-page Appleseedtale, plus reams of detailed information and art of the characters, machines, and weapons of Appleseed, presented in a non-Westernized, right-to-left reading format, as originally published in Japan.