Ockham's Razor states that simplicity should be the deciding factor when choosing between two identical designs.
In a world full of complexity, simplicity should reign. It is definitely easier to say than to implement. If simplicity is not a part of your creed, then trust me, complexity and difficulty will creep in eventually. The bigger the project, the more stakeholders on the project, the harder it is to keep it simple.
"Everything should be made as simple as possible, but not simpler." - Albert Einstein
The more elements you add to a design, the less efficient it becomes. Remove the noise, reduce the weight of the design to make it easily consumable. As you are trimming your design and making it lighter, don't compromise on functionality.
Ask yourself the questions, Why? What value does this element add to the experience of the design. Is it something you found on another website and though it would be cool to have it on your website? Don't get me started on tag clouds.
So as you are deciding between equivalent designs, keep in mind Ockham's Razor and you will have an effective way to select a design which will have the potential to create less problems for the user.