MacMini. I highly doubt you need anything the MacPro has to offer...the PCIe slots mainly. Those allow you to add capture cards for broadcast work. If you shoot tapeless, or firewire tape...then you have no need for the tower.
Plus, the MacPro you listed is 6 years old...the Mini...brand new. Don't buy into old when you are getting computers. They age too fast.
I have a MacMini server i7 (aka 4 core) and a MacPro 2008 eight core.
The Adobe apps benefit greatly from CUDA enabled video cards. The MacPro will do an AE encode in 1/3 the time of the MacMini because the MP has a nVideo Quadro 4000 card and the mini is using the on board video.
While the MacPro is getting long in the tooth, all its parts are replaceable. Not so for the mini.
Just sayin' ...