That's impossible to answer. What are you judging them on, customer service, shipping times, price, product availability, the type of products they sell?
You could ask that type of question to 10 different people and the chances are that you will get 10 different answers because some things are more important to different people.
You have to work out what is important to you and then base your decisions around that criteria, rather than relying on what is important to others.