_ It depends! Emulsions have water in them, so part of your freight cost is shipping water. They tend to have a higher viscosity, a lower price point, and extremely fast knockdown, even in cases where agitation is poor.
_ 100% active antifoams are concentrated to have a lower viscosity and a higher unit cost. The decision as to which is best for you depends on your specific application and on how well you can control antifoam usage. With better control, the 100% active formulations are often more cost effective. For a 'bucket-brigade' environment where antifoam dosing is hard to control, the lower unit cost of emulsions may be the better choice.