There is no one best exercise or exercise device to lose weight or get any other benefit. The best exercise is the one you'll do. When people choose something they like to do, they have a greater degree of success in sticking with it for the long term. To get the benefits, consistency is the key. See the prescription below for the appropriate exercise parameters for the goals you have in mind.
Exercise is one of the single most simple and effective means of improving overall health.
Research shows that even moderate exercise improves overall health. We know that the addition of exercise is a major factor in helping to lower blood pressure and to control diabetes. For some individuals, exercise can be the difference between needing medication to control the disease and not needing it. Some studies suggest that for individuals who suffer from depression, exercise can be as potent as drug therapy in helping to maintain emotional balance. Moderate exercise will promote improvements to total physical and mental health.