The definition of a best friend is a person who you value above other friends in your life.
someone you have fun with, someone you trust and someone in whom you confide. The first person you call when you get good news or want to go out for a bite to eat is an example of your best friend.
A good friend is like a four-leaf clover: hard to find and lucky to have. There is nothing I would not do for those who are really my friends. There’s nothing like a really loyal, dependable, good friend. Nothing.
By definition, no. Best means better than any other. If two friends tie, then neither is best. You can have more than one really good friend, but there can only be one best.