I agree with you Zonko that having read them all so many times it's difficult to separate them. I also agree with Wanna be when you say that it's hard to go past the first 'cause without that where would be be!! I love the 2nd/ CoS 'cause I did not see the Tom Riddle = Voldemort thing coming and I still remember the amazement of finding that out for the very first time. My fav. would have to be the 5th though because JKR managed to pack so much action, adventure and surprise into it. Unlike the 6th:

OK I'm gonna put myself out there as a target of your scorn and derision one more time when I say that I think the 6th book was not as well written as the others. I think who ever edited this book should be shot. It was too long and too slow. There were too many drawn out conversations; ....said Ron,.... replied Hermione, .... shouted Harry etc etc. Additionally, when you stop and think, what really happened in the 6th? We find out about the prophecy. That's it. Before you all start posting everything else that happened, STOP! I know the book very well. I know other stuff happened but if anything did happen that will prove important later, it was buried in a dull (compared to the others), turgid soup of Harry's hormones and unnecessary discussion. Where was the humour in the 6th? Even Ron was serious. Thankyou JKR, for Fred, George and Luna, our only sweetners. I did love the book, I'm on my fouth time of reading it, it just wasn't as good as the others.