I've always loved the classics by Leiji Matsumoto. (Galaxy Express, Captain Harlock) Additional ones are the original Gundam series plus War in the Pocket and Stardust Rising. Fantasy wise, Aesthetica of a Rogue Hero, Ah! My Goddess and Black Butler are always great. Additional Sci-Fi I've always enjoyed are STR.A.IN (Strategic Armored Infantry) and Sol Bianca.
Haven't picked up a Manga in years, but I should probably rectify that soon