It's pretty simple, what Batman comics are underrated, just right, and overrated. Keep it in Batman comics, no supporting character stories, i.e. Nightwing, Gotham Central, etc.
Underrated: Bane of the Demon, Slayride (Det. Com. #826), Face the Face, Dark Knight Dark City, Yesterday's Gone (Det. Com. #678), Heart of Hush, Prey (LOTDK), Battle for the Cowl, Noel, Gotham County Line, Resurrection Night (Batman #400),Wrath Child (Confidential), The Man Who Laughs
Just Right: The Cult, Morrison's Batman and Robin, Venom (LOTDK),Year One, The Black Mirror, Strange Apparitions, The Last Arkham (SOTB), The Long Halloween, Dark Victory, Gotham by Gaslight, Whatever Happened to the Caped Crusader?
Overrated: The Dark Knight Returns, A Lonely Place of Dying, Hush, R.I.P., Court of Owls, Arkham Asylum, The Killing Joke, Ego