Note that I'm giving weight to ambition here. A low-budget effort that succeeds is given extra weight. Similarly, a trivial piece of fluff that fails (Superman IV) doesn't count as much. Let's be honest here. You knew Superman IV was going to suck, so why even bring it up?
1. Superman: The Movie - An absolute classic. The folks who made the star-studded "3 Musketeers" movies in the 70's took well to the superhero genre with a film with tons of fun and heart. They also scored a home-run with flawless casting. Like all good franchises, it inspired a series of increasingly-worse sequels.
2. Unbreakable - Boy, now here was about the most innovative thing I've ever seen. A superhero movie that you don't even realize is a superhero movie until about 3/4 of the way through. A superhero movie that dispenses with the obligatory frenetic pace. A superhero movie that doesn't take place in an alternate universe where people just accept that superheroes exist. It screams for a sequel, but apparently M. Knight Shamalamadingdong has a bit of a thin skin and was offended by the occasional negative review.
3. Teenage Mutant Ninja Turtles - A great example of how to make a fun superhero movie on a modest budget. Yeah it's a kids movie, but it's still fun to watch.
4. X Men - I fully expected to hate this one, because huge budget superhero epics are rarely satisfying. But it had a good story and good action. I am, however, tired of seeing Patrick Stewart play the same character over and over again.
5. Batman (1989) - While this is a flawed film that suffers from Tim Burton's apparent need to film five minutes of nothing in order to make a really cool five second sequence, coupled with the dumbass choice to make a dark brooding film with a soundtrack by Prince, it was very influential, and it ended well. Like Superman, it inspired a series of increasingly godawful sequels.
Now the worst. Going from least-worst to worst worst.
5. Tank Girl - Boy, whatta disappointment to see a great edgy comic book made into such a dull non-edgy mess.
4. Tomb Raider - Basically a clone of The Phantom, which was basically a clone of The Shadow, which was basically a clone of a dozen other movies about some ancient doodad that's broken into three pieces and will cause all kinds of trouble if the pieces are joined again. The first time I saw this movie, I felt like I was watching it a second time, because I knew exactly what was going to happen next.
3. Blankman - Damon Wayans move from the top of his game with "In Living Color" to make this piece of crap. It's got too many turd-jokes to be a good kids' movie, but it's too stupid for adults. Apparently Damon thought he could just get on screen and do funny voices for 90 minutes and he'd have a hit.
2. Dick Tracy/Judge Dredd - Again, these are both basically the same movie, attempting to translate a comic-book world complete with garish colors to the big screen only to end up with a very expensive looking incoherent mess.
1. Captain America - This one was really hyped up in the theaters in 1991 (remember the shield-poster?), but suddenly appeared on video store shelves without a theatrical release. It's every bit as bad as the worst Superman or Batman sequel you can name, but it manages to do it in its first outing. Its only saving grace is that the producer realized he had a major bomb on his hands and cut his losses before tossing more money behind a big ad campaign and theatrical release. Something the Battlefield Earth guys should've figured out.