The famous five series is the best to start with and to inculcate the reading habits in kids.
With the famous five and the dog out on finding solutions to new adventures... mysteries..... its all very exciting..with Mr Goon (the policeman) and the friendly sergent.... good to tell you difference between right and wrong.
Very thrilling and original... full of fun and mystery all the way through be it.. The mystery of disappearing cat or The mystery of burnt cottage... all are excellent readings for children in the age group of 10-15...
Enid Blyton knows his target readers and fulfills their need to great extent. Also some of the words may force kids to refer to dictionary, which is again very useful....
Bottomline: A very good platform to build reading habit...