To little information to offer any advice.
A good choice for what?
Are their any other features on the camera?
The truth is you can make a documentary on any camera.
The iPhone, the Flip, a camcorder, a pro camera, a DSLR.
It isn't the camera choice that's truly important, it's what
your documentary is about that is important.
But a 24p camera is fine. Make sure it has a mic input and
manual controls over white balance, exposure and iris.