B.C.
Both my 15 year old and my 10 year old have always been readers. We loved the Harry Potter series. I was not a big fan of The Series of Unfortunate Events, but the kids seemed to like them. I liked the original Boxcar Children book and they made it into a series of chapter books. I adore the C.S.Lewis series The Lion The witch and the wardrobe and so did my son and daughter.
My daughter liked Junie B Jones, they were not too bad, I preferred the Beezus and Ramona books...I read everything my kids read, the reason is it makes for great conversation opportunities. Also ask at the local library, they love to recommend age appropriate books.