 If you liked
Toaru Majutsu no Index
|
 ...then you might like
Sword Art Online
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Both series have supernatural and fantasy elements as "regular" parts of life.
Personally I believe that you either love this series, or you simply can't handle all of the many different elements and sometimes religious motifs used in it. Also, both have romance, action, and a "righteous" MC and both have their cute fanservice moments as well.