Liquids supplements are easy to absorb but require heavy dosing in order to achieve desired RDA allowances. They are cumbersome when traveling and tend to taste unpleasant. Often the taste must be disguised by some type of sweetener. Some sweeteners are harmful while others are perfectly acceptable. Know which sweetener is in the products your considering.
Capsules tend to be the industry's favorite.
The capsule is usually made of gelatin allowing easy breakdown of the nutrients inside. For the vegetarian there are capsules made from vegetable sources although they tend to cost more. Like tablets capsules can have fillers. This is done primarily to make the capsule look full and act as a non-caking agent. Absorption of nutrients can only be attained by the proper catalyst accompanying it.