 If you liked
Toaru Majutsu no Index
|
 ...then you might like
Fullmetal Alchemist: Brotherhood
|
Both series deal with mature teenagers going through a great struggle to achieve some bigger goal, going to particular adventures, and fighting for their lives. All the hardships they go through, together with friends and comrades, are in both series almost similar. Sometimes the characters are a bit more childish in FMA:B, but both series deal with a lot of the same elements.