All are good products from good companies. Generally, we consider the decision one of cost. For single user installations such as at home or in a small office, there is virtually no difference in price. From all that we can tell, virtually all of the common viruses are detected by all of the virus detection systems. All of the virus protection programs use CPU or processor cycles, so all of them tend to slow down the systems they are loaded on.
None seems to be significantly better than the others.
Computers we have installed in the last 3 months contain Norton Antivirus from Symantec. Before that, we tended to prefer McAfee. The main reason we switched was that we liked the new automated download features in Norton better than McAfee's version 5.0 product. We could change our mind at any time. Virus definitions even a couple of months old are too old to be any good.