If you desire to do aerobic training, your selection of equipment and type of training to do is quite diverse. If you go to a gym you have many choices: elliptical trainers, steppers, treadmills, stair machines, swimming, cycling, upright bikes, recumbent bikes, etc.
The answer to which equipment you should use lies in your preference. Select the one you feel most comfortable with and which you enjoy doing. Studies show that there is no difference in relation to the amount of fat or calories burned between the different equipment. Perhaps even more important than which type of equipment or activity you should use, a combination of several may be more advantageous. The key is to increase your metabolism and this is very effectively done by training relatively hard for a short amount of time rather than going for long distances or periods of time at a lower intensity.