Hhmm, I think my favorite arc might be Lady Jessica. She kind of has this pivotal point in a multitude of storylines and her becoming a Reverend Mother in a way she never thought she would was very interesting. She was obviously a supremely talented Bene Gesserit and I think her decision to bear a son indicated that she was so unconsciously connected to the BG breeding plan that it was an instinctual answer to finding the Kwisats Haderach.

There were so many great arcs though, I also really, really, loved the brief glimpse into Pardot Kynes arc that was at the end of the appendices. I wish that there could've almost been a more dedicated prologue characterizing him a bit more.

As for my least favorite story arc, I was pretty unimpressed with the way Liet Kynes died. I thought his death scene was well written but I wanted more from his character. I thought there was more potential with him but I think Herbert may have killed him to kind of even the playing field between Paul and the Fremen, they both lost their fathers. I also thought The Shadout Mapes was killed just a little too early. But these are relatively minor complaints.

One unanswered question I have is that I could've sworn multiple times in the book it was mentioned that a side effect of Spice addiction was prolonged life and yet I was pretty sure some of the birth/death dates for some of the characters (Lady Jessica chiefly on my mind) only barely made it to a hundred years old after being on a spice heavy diet for a multitude of years.