A lot of UnitFrame AddOns have portrait support. Which feautures are you seeking in a unitframe addon (how customizable should it be, are you fine with editing lua files?)
GrimUI uses ZMobDB for the animated character models. It's a separate AddOn from the unit frames and can be used in conjunction with any Unit Frame mod or stand alone.\
As also mention, Pitbull can have the option to use the character model, there are others however which ones escape my mind at the moment.
I have heard of others, many have said pitbull does it. Zmob is what is in the GrimUI however it has a few bugs in it i will warn you now. The version that comes with the grimui has had minor tweaks made to fix a few of the errors it was presenting. Also Zmob is the only 3d model addon that has even a fraction of the animation features. Although right now no addon does this but those 3d models are capable of displaying every action made by you or any other player. And a wide array of actions by npcs and mobs. Zmob is the closest thing right now. The 3d model code that came with MazzleUI did exactly what im talking about. Unfortunately it no longer works and he wont release the code.