Depending upon your situation, that will depend upon which tactic for marketing will be better for you. Some will want logfile analysis and others may want page tagging. If you are strapped for money, you may want to go the route of page tagging. That is because page tagging is less expensive. However, if you are wanting more accuracy, then you should probably choose logfile analysis.
It collects data and stores the data on the server. This makes it to be better if the company makes changes frequently to their data. Therefore, the log file analysis is your best bet for web analytics if you have the money to spare. The second would be page tagging especially if you don’t have the money.