So far I've ranked the Batman movies, the Superman movies, the other DC movies, the Avengers movies, and the X-Men movies. There's only one major franchise of super-hero movies I haven't ranked yet, and that is the Spider-Man franchise. But for now, let's rank the comic-based movies that aren't based on DC or Marvel superheroes.
As ever, my ranking system is
Green=excellent Blue=pretty good Black=Okay Red=avoid
American Splendor--Based on Harvey Pekar's autobiographical comics about life as a blue collar worker in Cleveland. Parts of the movie are "real", with Paul Giamatti playing Pekar himself, other parts are animated. Includes all the famous episodes--Pekar's friendship with cartoonist R. Crumb, his appearances on David Letterman, his work at the Cleveland VA hospital as a file clerk. Highly, highly recommended.
Conan, various movies--I've decided the Conan movies are based on R.E. Howard's original stories, and not the 1970s Marvel comics, so these don't earn a review.
Crumb--About the life of underground cartoonist R. Crumb and his exceedingly strange family. Robert Crumb and his two brothers grew up with a brutal, physically abusive father and turned to drawing their own comics as an escape. They continued this practice into their teenage years and beyond, with Robert especially sublimating his repressed personality and sexual desires and frustrations into increasingly bizarre comic art. This became the basis of a whole career for him, producing such 60s comics icons as Fritz the Cat and Mr. Natural. The movie is endlessly fascinating and most certainly not for kids.
Creepshow--A horror film based on the spirit of the old 1950s Tales From the Crypt comics, but not on any particular stories that were actually published. As with Conan, I've decided these don't meet the threshold for inclusion.
Fritz the Cat (1972)--An X-rated animated movie based on R. Crumb's stoner, ne'er-do-well cat. Do not, do not show this movie to your kids. But don't show it to your adult friends either. It feels highly dated, the racial and sexual scenes are just embarrassing, and it is awfully hard to get through.
Heavy Metal (1981)--Unlike Fritz the Cat, and perhaps this is just personal bias showing, but I find this film to be the height of lurid pulp entertainment. Taking several of the best-loved stories from the long-running science-fiction comics anthology magazine Heavy Metal, adding a hard rock soundtrack anchored by Sammy Hagar, and not toning down the sex, nudity, violence, and weirdness of the original material one bit, this movie achieves a sort of dream-like id-driven erotic nirvana. Voice work is done by John Candy and Ivan Reitman, among others.
Judge Dredd--Haven't seen
Mystery Men--Reasonably amusing send-up of superheroes based on a popular DC comic from the early 1990s.
Sin City (2005)--Ultra-violent anthology with stories from Frank Miller's popular 1990s comic. Noir atmosphere and truly over-the-top murder and mayhem featuring bent cops, femmes fatale, and private eyes.
Sin City: A Dame to Kill For (2014)--Haven't seen
V for Vendetta--Haven't seen
Watchmen (2009)--This 1986 comic by Alan Moore featuring superheroes facing the real-life consequences of their actions is considered one of the finest comics ever made. A nearly scene-for-scene transfer to film somehow results in a fairly mediocre movie. Huh. I've re-read the comic lately, it's still pretty good, you should read it too if you haven't yet.
Here's the master list of all comics movies I've rated so far, in order from best to worst:
Heavy Metal (1981)
Batman Begins (2005)
Captain America 2: The Winter Soldier
X-Men 2: X-Men United
X-Men: Days of Future Past
The Dark Knight (2008)
Iron Man 3
Sin City (2005)
X-Men: First Class
Swamp Thing (1982)
Iron Man 2
Batman Forever (1995)
Superman Returns (2006)
Thor 2: The Dark World
Incredible Hulk (2008)
Dark Knight Rises (2012)
X-Men 3: Last Stand
Fritz the Cat (1972)
Batman and Robin (1997)
Batman Returns (1992)
Batman (1966) (Haven't seen)
Catwoman (Haven't seen)
Constantine (Haven't seen)
Green Lantern (Haven't seen)
Hellboy (Haven't seen)
Judge Dredd (Haven't seen)
Man of Steel (Haven't seen)
Sin City: A Dame to Kill For (2014): Haven't seen
V for Vendetta (Haven't seen)
X-Men Origins: Wolverine (Haven't seen)