So many to choose and different characters are stronger in different books.
Arya's journey up until she left Harrenhall is one of my favorite pieces of the novel.
Tyrion's were consistently good until he murdered Tywin.
Cersi's slow decent into madness where it showed her thought process in scheming were really entertaining. Especially on a second read where you know her schemes don't work out.
Wasn't into it the first time as I was more plot driven - but the second time I read, Bran's entire journey was probably the most entertaining.