I agree Zbrush is probably the most popular 3d software around today.  Used by almost everyone.  If you wanna get a job in 3d, seems you must at least know your way around Zbrush.  I understand it's a super powerful application, but I personally hate it.  Such an unintuitive and hard to use interface, it makes Blender seem like a child's learning game.  I'm in the total minority on this, I'm sure.

If I decide I must sculpt something, then I'll pick up Sculptris once in a while, and I have tried 3dcoat, and found it much easier than Zbrush.