Ok, so there's a thread ongoing in the Menoth section on the big boards, about who is going to be the best caster in a competitive tournament setting. Now, I don't play in a lot of tournaments and for the most part, I'm a casual player so take this into consideration when I rank them.
As you can see, I think all of the Menoth casters are more than capable of doing their job. The only reason the Harbinger is Tier 2 is because of the immensity of putting together the model. It might take someone longer to do this and cut back on playing time.
When people see caster rankings it sometimes sways an individual to not even try to play a caster. That's why I have everyone at Tier 1 save the Harbinger, which is just a joke. It's a good way to encourage people to try out all the faction casters and increase your gaming skills.
Let's not think of reasons why one caster is the top dog but try to come up with new strategies for them instead. It will help broaden your knowledge of models and help come up with the not so obvious combos. In the end, it'll be more rewarding for you as a player. That's my 2 focus for the day.