If it is for Film making the difference in pixelcount doesn’t really matter between the two.
The size of the sensor does tho.
You have to ask yourself what kind of shooting you are gonna be doing.
If you plan on using al kinds of crap attached to you camera the the 5d or 7d might be the way to go (Im talking follow focus, external monitors, steadicams etc.). But if your work just involves hand holding or a tripod the the 60D is best. The flip out screen and better audio features makes the 60D leave the other two in the dust as a “Naked” camera. (stricktly i terms of video, Still photography is another story)
Basicaly the difference in videoquality between the models is unnoticable to most users.