This list is super long, so I'll keep it down to 5-10:
1. She's a great author, with a multitude of books that can fit any person's interests.
2. She is a really cool friend, honestly I have proof.
3. She is the greatest at Quidditch (we're on the same team)
4. If you follow her, I'll follow you back
5. She has created SOOOO many great groups, literally it's like she makes one a day
6. She is super loyal to her friends and such
7. If you still need more reasons, idk what to tell you. She's super awesome, there's not a single reason NOT to follow her.
8. She's all for rights and representation of people, and fights against discrimination.
9. She writes a bunch of great articles for my newspaper, so if you're a fan of TDP (The Daily Prophet) you know who to follow.
10. She's at 91 as I am writing this, so she only needs 9. Your follow will count for 11% of her happiness for getting 100 followers.
There, I kept it down to 10. Please follow her, then post on my wall that you followed her, then I will follow you back.