The second fastener to which you refer is commonly called a "Molly" fastener. You can get several strengths of either type to insure that you can hang what you need to. One of the big advantages of mollies over toggles is that once installed, you can remove the screw from a molly and replace it. If you remove a screw from a toggle, the toggle part falls down inside your wall. Another good feature of mollies is that you can get a type that you drive with a hammer, eliminating the drill step. Chris is right, though. Go for the stud if possible!