The Japanese poster for Jean-Pierre Melville’s Army of Shadows is a classic. Suspiria poster is a classic. The Hong Kong poster of Tsui Hark’s Blade that scrolls out like this 40x8-ish poster is amazing.
Beyond that it would depend on what your looking for. More of an original painting (French), abstract (Polish), contemporary/traditional (US) or more edgy (Spain, Italy) or more collage-esque (Japan).
Additionally Italian photobustas (nearly double the size of a lobbycard) make great artwork for decoration.