IMHO, the Fear is just big open chunk of land - nothing really interesting there
Hate - confusing, doesn't really ties with "hate" at all in my mind
Now Sky - was a pinnacle of raiding, with all the islands and keys and riddles and so on, but time invested vs rewards gained was prabobly WORST out of all 3 original planes: there few uber items, but amount of time it took to obtain them, was simply outrages.
I myself never got into raid level until it was already PoP time, so to me, the bets of the best raid zones were Vex Thal (3 months key farming was totally worth it at the end), and from PoP Plane of Torment was my favorite. I also really liked Barindu, Riwwi and Ferubi - they were simply marvelous (never got past Kod Taz thought). I loved and feared at the same time, how devastating GoD mobs were, but rewards were equally amazing.
Out of zones that came after my time - Anguish, Riftseekers, and Dreadspire prabobly some of the most amazing zones