THE CROW: CITY OF ANGELS
Of the two movies on here, this is the one that I want to see get an extended cut the most. While the film itself was heavily flawed throughout, this was only because the studio wanted to make it "more like the original" by cutting it's original two hour plus runtime into a dismal hour and a half. The film had a tacked on "happy ending" thanks to this decision as well, not unlike
Blade Runner's theatrical release, and it unfortunately undermines the sense of tragedy that the filmmakers were intending to portray. The script was written by David S. Goyer, and from my memory of watching the PPV version, which restored most of the original cut's footage, it seems that he had assembled a pretty solid script that explored more ideas around The Crow, Ashe Corvin in the film, as a tragic character. For example, unlike the happy ending that was inserted at the last minute, the original ending depicted a much more devastating finale that actually denies Ashe of his own death, which means that he'll forever be stuck as The Crow because of his own choice to stay and fight for Sarah, but, just like in the original ending, she dies, and Ashe is left with nothing in return. It would have been a great ending, and a better lead-in to future sequels (or just the perfect ending they were looking for).
Here's a list of the scenes that were removed.
SPIDER-MAN 3

The hate this film gets is baffling, but it's obviously because of the fact that there's just a lot missing from it. From the Comic-Con trailer that was leaked years ago, there were a ton of interesting moments that could have added more to the film, like when Peter is staring at himself in the mirror and then, out of nowhere, that Venom looking thing (from above) pops up, also there's a shot of Sandman intimidating a doctor and there's a very brief shot of what appears to be Venom trying to ruin Spidey's face with his webbing. Personally, I'm fine with the way the film is, but there are a lot of things about it that could be trimmed up a bit, and there are loads of stuff left on the cutting room floor that could make for an even better movie than they had originally released. They even shot an alternate scene of Eddie convincing Sandman to join him in fighting Spider-Man and, judging from the set pictures of the scene (found in the link below), it would have been a much better, more coherent scene to have in there than when Venom (quite literally) randomly finds Sandman. Also, I want a final swing.
Here's a list of the scenes that were removed.