It's interesting, because Iron Man wasn't really ever a top tier Marvel character, but it was a master stroke that they got Robert Downey Jr to play the role of Tony Stark, and he took to it like a fish to water. Blade also worked because they perfectly cast Blade with Wesley Snipes, and the script and directing was really good. The budget was also modest, so they don't have to keep sinking these $200 million budgets into these things. Some clever directing, writing, and production staff can shave a shit ton off of the budget.
DC has some heroes worthy of film, like Green Lantern, Flash, Wonder Woman, Martian Manhunter, etc, but their method of going about bringing those guys to the big screen has been atrocious.
How the DC origin movies have failed, while the Marvel ones have flourished are beyond me.
Green Lantern was an amazing opportunity to have an awesome "Space Cop" film, with Hal and the Corps patrolling the galaxy kicking ass and dealing with intergalactic threats, setting the stage for a potential conflict so big that the Justice League would have to be brought into the mix. It would also be a great opportunity to bring in Superman's world, as Krypton could be name dropped as a planet in a sector that one of the GL Corps failed to protect.
Wonder Woman isn't as hard to bring to the big screen either. They just need to drop all of the ridiculous tropes that surround female protagonists in film. She's basically god tier, like Superman, but she has more of a gray area of morals in comparison to Superman and Batman. A movie focusing on her could have her wrestling with that strong, aggressive Amazonian side, and her role as an Ambassador.
Even Aquaman could be turned into an awesome movie, without having to resort to dudebro "XTREME!" measures.
It's all about the strength of the casting, director, and screenwriters. Marvel took that shit seriously, and look at the results.
It's obvious that DC and Warner Bros just doesn't give a rats ass about the DC roster that isn't Batman and Superman. They barely care about Superman.
Respect the property, and get filmmakers that respect and understand the property, and maybe, just maybe, you'll get some of that sweet profit pie that Marvel has been munching on for a while now.