Toaru Majutsu no Index, Durarara!! Recommendations
Both stories have very big settings.
Both stories feature organizations' conflicts
Both stories have some creepy characters.
Both stories have massive amount of characters. Currently, Index>Durarara!! though.
Both anime show us story about big city life. There are few organisations fighting with each other and on the other side we can see daily routine of quite untypical teenagers. Both series have a large number of heroes. Each of them has its own personality, individual traits, habits and vices.Their fate is often intertwined with each other, complicating the whole story-line. Consummate sociologist will definetly find himself in both stories. However, the plot in Durarara!! is conducted in more mature way.
Both are supernatural action/drama/comedy storylines (although less of the comedy in Durarara and more of the action in Index). They both take place in epic urban settings and incorporate science fiction and fantasy into the same world in interesting and creative ways. The supernatural elements of both shows are explained just as much as they need to be and are really cool to watch.
The characters are pretty different, although some parallels can be drawn between the supporting cast if you really try? But the main characters (Touma and Mikado) are both the same sort of "not necessarily a nice-guy-stereotype but incredibly moral and dedicated
Both shows feature or include the following:
A large cast of interesting and varied characters.
Excellent openings, endings, and backing tracks.
Mystery and intrigue balanced with action and humor.
Over 60 episodes.
Vending machine violence.
The shows certainly are not identical, but they share similar vibe, scope, and appearance. If you liked one of these anime it should be worth taking a look at the other.
Both are action thrillers and feature a somewhat overpowered female protagonist.
Also share the Yakuza theme (Yellow Scarves x Dollars, Accelerator x Misaka etc.)
Both anime take place in a big city where many gangs roam around and supernatural elements occur. They have a huge cast filled with unique characters who can be similar to each other. You've got a main character who appears generic, but is somewhat out of the ordinary; a badass main female character and one of the craziest people you'll ever see. They also feature lots of action, lots of mysteries and a few humor thrown into.