As a fan of The Famous Five, who spent many a rainy day engrossed in their adventures, I agree she is tops....though maybe not number one. Pity about Pullmand, I think he is an excellent writer but unlike Rowlings, the reader is actually expected to think about the subjects and stories covered.
Our youngest grandchildren have just been introduced to the Secret Seven and are absolutely spellbound. Whilst reading classic stories for the second time around to all of our grandchildren (now aged from 16 to 5 years old), I personally was more concerned about Lewis Carroll - definitely on drugs!!! and Charles Kingsley!!!!
I saw the film version of the Water Babies before I read the book, and I think the director's were definately trying to beat Kingsley for strangeness
I read Enid Blyton as a child, and my daughters read them now. The older one has read the Harry Potter books, and she still goes back to Enid Blyton (and the Beano). Its a shame WE Johns and the Biggles books didn't make it into the top 50; he was the author that I graduated to after Blyton and far more influential to me.