I wouldn't use either. There are a lot of really good free choices out there such as avast!, Comodo, Panda and MSE. If you want to go the paid route, then avast Internet Security, Norton, Kaspersky, G Data, ect.. are all better choices then McAfee or Trend Micro.
But if your heart is set on one of those two, then I would go with Trend Micro all day over McAfee. Head over to http://www.wilderssecurity.com/index.php
and look around for a while, and you can make a much better informed decision.
Quarter 1 2011 tests: http://www.av-test.org/certifications.php