The order and POA are my favorites. Harry having no family but the dursley's? i mean, come on....the kid already lost his parents, but having to spend his summers with the DURSLEYS? honestly tho, Sirius coming in, that was awesome, and harrys firebolt? zoooommmmm, and then the order because now we're getting in to the action, where all the slates are getting brought out and shown to everybody, how lily and james were found by voldemort thru pettigrew, and just how important the prophecy is. My favorite scene out of all the books tho, is between the dragons in book 4, or in book 5 down in the ministry's secret hall....im a HUGE dragon fan....and any other dragon lovers, i recommend Eragon, and Paolini's new one, Eldest.
For me, it goes 4, 3, 1, 2, 5. I didn't like Order of the Phoenix that much cuz Harry's entire personality just changes too much. He just kinda turns into a whiny lil self-pitying b!tch. My biggest critique on the series as a whole is also that JK kinda tends to re-use stuff, which makes the world seem smaller and almost less grand. Crouch using Polyjuice Potion and the unregistered animagus, for example (you know, besides the other 3, even though there are few REGISTERED ones, and its supposed to be a very difficult process and all that). Don't get me wrong, I'm as much a Harry Potter fan as the next guy, but honestly... think of some new stuff...