Aa! Megami-sama! (TV), Chobits Recommendations
They're both harem with incredibly beautiful girls. Both guys are loserish guys who get a hold of their love interests in interesting ways. Ah! My Goddess has less of a plot than Chobits but both are great fun.
Unlucky guys meet beautiful girls and after living together they fall in love with them
Another example of the magical or mysterious girl concept. Both series deal with 'fish out of water' female protagonists who come across as naive, but in matter of fact are both powerful entities with the immense power to affect massive changes in both of their respective worlds. But despite that both shows spend a lot of time on romantic development between mortal men and these mysterious women who enter their lives and alter them irrevocably with relationships which are far from the conventional they seem to be at first glance. A great example of these deeper implications shared between the two shows is the mortal