Skid Steer Loader brushcutters make clearing thick brush, small trees, and other vegitation easy. Knowing what your job requires will give you good insight on which one to use.
Closed Front Brush Cutters are better for clearing grass, weeds, undergrowth, and small trees (recommended 3" and under). It keeps debris contained instead of flying out, making cleanup fairly easy. They mulch leaves, limbs, and saplings into small chips and pieces leaving behind a cleaner, more consistent cut than open front brush cutters.
Use an Open Front Brush Cutter when you need to mow down large areas of extremely tough brush. Cutting through dense brush and trees up to 10" in diameter are what these are made for. These Cutters are ideal for cutting tree stumps close to the ground, cutting new or maintaining trails, land clearing for properties, etc.