The higher up on the pyramid the evidence, the better the evidence.
When using the word evidence - think of the word research or journal articles. The better type of research to answer a question, the better the answer.
Example:
You have a journal article about bruxism which is an RCT (Randomized Controlled Trial) and a Case series on bruxism. Which one is better? The RCT! Why? It's higher on the evidence pyramid.
There are many different kinds of EBM pyramids. This is a basic model.
Decisions and Evidence in Medical Practice by 
Evidence-Based Medicine by