 If you liked
Nana
|
 ...then you might like
Kanojo-iro no Kanojo
|
Both manga's depict close friendship between two very different girls who end up living in the same appartment: one who is following her dream and is self-sufficient, and the other who has no dream but is constantly falling in love and moving from relationship to relationship.
Nana is more full of drama and is (in my opinion) better, but kanoko iro no kanojo has at least an end (Nana has currently been on hiatus for two years) and is quite a nice, well thought out story.