There are many individuals that have been taught that cardiovascular training is the best way for a person to lose weight and stay in shape. There are others that will argue that Resistance training or weight training is the better way to go. It actually might come down to one thing. It might simply depend on what you are willing to stick to.
A good cardio workout a few times a week is likely to keep you in shape if you are already there, but you will need to work out almost every day if you want to get the weight off and keep it off. Many cardio training techniques do not help with toning the muscles; they only get rid of the fatty tissue surrounding the muscles.
Weight training or resistance training can give you the best of both worlds. You can get a cardio workout with your weights if you keep moving. You at the same time will be able to get the toning that is needed to make it look like you have been working out. If you are looking to build muscle then use higher weight, If you are looking to lose weight then use a lower weight and do more repetitions.
It is up to you to decide which will greater benefit you. You might find that doing bit of both will help to mix up your routine and keep you at the gym. Mix up different types of exercises as well to keep yourself interested.