Here is a list I've compiled of my favorite authors. If you are looking for a book to read to your class, anything written by any of these authors would be a good choice! :)
Note: If I find a book by any of these authors at a thrift store, even if I haven't read it, I will usually purchase it because I know it will be good!
I will add more as I think of them. My books aren't in front of me right now- but these are some of my all-time favorites.
Gary Paulsen (usually for 5th grade and up...although his work is AMAZING, it is often pretty graphic)
Cynthia Rylant (my absolute favorite author!)