Junie B. Jones books are sort of a controversy with some parents and teachers. Junie B. is a sassy little girl (early books she is in Kindergarten and then 1st grade) who has horrible grammar. A lot of parents don't like how sassy/smart mouth she can be, and a lot of teachers don't like her incorrect grammar. I first heard of Junie B. Jones when I was student teaching. My cooperating teacher read the series to her students. When she would read out loud, the kids would correct Junie B.'s grammar; that's how the teacher handled it. If you can get past the sassy talk and incorrect grammar, these books are SO FUNNY. I don't read them out loud to my students much any more (because they read them aloud in most of the 1st grade classrooms) but when I do, I am laughing out loud with the kids. If you are unsure if your child should read these books, I suggest checking out one from the library and reading it first.
Clementine is a little girl a lot like Ramona. These books aren't as long as the Ramona books, so they would be a good place to start. Girls usually really like this series!
The Magic School Tree House books are always a good choice. Each book is based in a historical location...sometimes a real event, sometimes not. What is fairly new is the "Fact Tracker" that they have started writing that goes with each book. It is a nonfiction version that tells about facts found in the fiction version of the books.
Let me start out by saying that I had to really convince myself to add this series to the list. These books are full of crude potty humor (obviously), but boys LOVE them. If you are having a hard time getting your son to read, you might try these books...if you can look past the stupidity!!
The movie made these books more and more popular. If you haven't read them, it's worth a try. They are silly and funny. I've found that both boys and girls like them.