Do you think it's better to teach English grammar through stories or topics?

Yes it is very beneficial to learn through stories and topics. It is also interesting for students to do role modeling or acting in a play.

Yes, learning process and teaching will become easy for both the students and the teacher respectively.  The students can associate tenses, Concord(agreement of verb and subject), number with the story.  This method will be greatly interesting for both the parties.

assalamualaikum according to me children love the games 

so education should in a play way method so easy to grasp every thing by a small memories

its better to proof than shouting at them

jazakallah

I personally encourage it. The students can learn how to compose sentences from how a story goes.

If the protagonist (hero) did something, the past tense rule will be used. If he or she decided to do something, then the word "will" will be used.

Sure yes, that will be an effective method to learn grammar;  grammar means structure so both must no separate  each other

Yes Of Course. Grammer is integral part of English Language. And it is very effective method to teach grammer by the help of stories or topics.

thanks for the invitation

Yes, of course they are often more fun and interesting