Quite out of touch with the topic in general but I'll give it a go from what I remember.
Subsidies you would generally talk about their purpose and what they hope to acheive..in this case to increase consumption. A clear disadvantage here would be that firms might get use to receiving a subsidy and so would become inefficient as time goes on. Also as subsidies are payed through taxpayers money there might always be a better option to allocate funds towards. However some goods despite making firms inefficient would not be produced at all if it were not for subsidies. ( this would generally be your conclusion I suppose ).
Taxes would discourage the consumption of a certain good. Advantages are that they keep production/consumption in-check and would lower social costs or negative externalities etc. Disadvantage would be that it is quite hard to determine the appropriate tax for a specfic good. It is important to help society as a whole and remain profitable to some extent for the producer..there needs to be a balance between the two. Enforcing the taxation always requires funds and may not always be possible. Taxes may encourage illegal activities such as tax evasion. Another more obvious disadvantage is that they do not account for other reasons such as consumer confidence. If consumer confidence is high taxes will not discourage consumption and so will fail in its overall purpose.
Your conclusion should generally be a balance between both points depending on the issue at hand. Depending on the good neither taxes or subsidies may help and a total ban may be required. Smoking addiction is one such good that holds priority in this case (taxes would not really stop consumption by much if confidence or in this case addiction is the problem). Hope you get my point..theres no right or wrong answer..just depends how you express it.
