Standing Punching Bags:
If you plan on kickboxing, definitely purchase a standing punching bag since standing bags start much lower to the ground and are often height adjustable. The base is normally filled with water or sand. Sand will give you a more sturdy base and will rock less when hit. Some say stable is better but a little rocking is more realistic since your opponent moves with your punch. To incorporate the fluidity into the stand, water is much better. A water filled standing base is around 300lbs. One of the big disadvantages to standing bags is they are normally of lesser quality and are more likely to wear and tear.
The Hanging Bag:
If you are not into kickboxing and you are after a more durable, more professional punching bag, the hanging punching bag is best. Mounted to the wall or ceiling with chains allows the hanging bag to sway upon impact, better representing an actual opponent and allowing you to work on combos and footwork. Another key thing is the hanging bag will always return back to its original position while the standing bags are likely slowly slide across the floor, never returning to their original position. Please, please, please, before purchasing a hanging bag, check the weight of the bag and ensure your ceiling or alternate support can safely support it.
How much sway should there be in a Hanging Bag?
A bag should sway a little so that your dont break your hand upon impact, but not so much that the target is constantly moving and its near impossible to land a punch. Sway for a hanging bag is really determined by the size of the fighter and the weight of the bag. For a 510 180 lb. male, a 70-80lb bag will work. This is just a rule of thumb and those who throw lighter punches should aim for 50-60lb bags while those who really wish to throw some of the harder punches can go to the 100-120 lb bags.
To keep in mind:
It is recommended that you always use some type of hand protection when working the bag. Although serious bag injuries arent too common, its pretty terrible to admit that you cant participate in the actual fight because you broke your hand on the bag. As far as hand protection goes, it can be pro gloves for a boxer, striking/grappling gloves for those into MMA or possibly just hand/wrist wraps. Please use some type of protection though- Its better for your bones and will result in less wear and tear on the bag. For those planning on using less hand protection, you may want to consider a lighter bag to avoid potential injuries.