hello
i use Art-cam to Model/sculpt faces or anything organic, it is an expensive program at around five grand but i use it commercially and it was provided by the company..however there is a forum for art-cam users who will sculpt for you ...other than that there is an app called mud-box from alias and also there is z brush from pixologic..all these programs require some extensive work coming to a usable workflow but if you are artistic they are the bees knees, and a real compliment to a wacom.
mud-box is about the most versatile for freeform organics in a simple fashion
z brush is a steep but rewarding learning curve and art-cam is the type of software used by industry for routing wood or metal but is hight field technology or is "flat" 2.5D ..mud-box is 3D
there are apps geared more to animation then Modeling in which the mesh is manipulable like hexagon or maya, or any other "subdivision modeler"like studio max ..cheetah for mac.. They normally require the use of bones and constraints that move the mesh in scale and dimension giving the "movement" through animated key frames.
Google virtual clay or subdivision modeling look also at sensible technologies ...awsome.......for me anyway 😄