I have Cocktail, OnyX, MacPilot, and TinkerTool System. And at any given point in time for any given situation I may use any one of the four. However, each has its strengths and weaknesses.
  • Cocktail is the only one of the bunch that can be set to run and perform specified tasks automatically. I used to run several things such as permission repair every week using Cocktail, but that began to seem unnecessary and I no longer use the automated functionality of Cocktail. Others will certainly differ with my current practice -- it is most a matter of personal taste and opinion.
  • OnyX has the undeniable advantage of being FREE.
  • MacPilot has a growing list of "Tools" such as rebuilding the Launch Services database but it lacks features offered in most of the other utility apps mentioned. MacPilot's primary usefulness is providing access to over 1,000 otherwise hidden preference settings in almost every OS X app as well as the system itself. I am continually amzed by the number and variety of hiddes preferences in MacPilot.
  • TinkerTool System offers configuration and tuning tools not otherwise available in other apps as well as a tool for creating and managing Access Control Lists which is seldom needed but invaluable when it is needed. As I mentioned before, I find TinkerTool System offers more fine tuning options than others and has become the utility I go to first when I want to do something. But that is a matter of personal taste and others can and will disagree with me on that.

If we knew what it was we were doing, it wouldn't be called research, would it?

— Albert Einstein