I believe the most popular pick would be the Immortis due to people using math to find out which one is most effective ( I prefer the way Stalkers look), and the current meta really relies heavily on having at least some rend so spears are not the way to go especially since you can't get the big 40 guard blobs anymore due to reinforcements.
I have heard that Nagash lists have been quite strong lately but that is most likely due to the current god dominance meta. If you want a strong caster you can always get arkhan he has a good points value.