Food supplements when used for dieting should be used to supplement the diet and not take over it. A few of the top brands can be beneficial for convenience and nothing much more. The majority of food supplements on the market are made of a list of cheap processed ingredients mixed with artificial sweeteners. You have to pay serious money to get good quality food supplements. Saying that, people are paying good money for inferior quality products.
In my opinion you are better off spending your money on real food and getting your nutrients from food. Food from organic and free-range sources is far more superior to powder and tablet concoctions or bars. My recommendation is to use food supplements only when absolute necessary when all other options are gone.