So - this one is probably one of my least favourite HP-Book, which doesn´t mean that I didn´t love it! 

My personal favourite plotlines:
- Sirius - from godfather, to letters to fireplace conversations!
- Harrys arguement with Ron (only because I loved how much they missed each other and I think Ron deserved to snap - even if it wasn´t justified)
- every foreshadowing (Moody, Voldemort, ...)
- the graveyard scene (especially Priori incantatem?)
- the interrogation of Barty Crouch Jr.
- the aftermath

So, overall I loved almost everything about this book - except the Triwizard Tournament :)
It´s just not that ... interesting? Well, it is interesting, but not really my thing :)

My personal least favourite plotlines:
- Harrys argument with Ron (only because I hate seeing them apart and they were both so fricking stubborn ...)
- quite a bit of the Triwizard Tournament :)

All in all - I still love this book, but I was in my "ATYD"-Era and it just fell a bit flat :)