When working with people you may not know, that could be a good thing to allow for different ideas to come about. If you are not used to working with a certain person it may take some time to develop a working relationship, but it could lead to some great ideas that would have not been thought of otherwise. When working with friends, that could always be good since that working relationship has already been established. Sometimes working with friends could lead to arguments since people may be comfortable with each other, but at the end of the day that should be put aside to complete the task at hand.
No matter what the situation though, working with someone who is more knowledgeable than you would always be ideal. Learning from those who are more experienced will benefit the project team so much. That experienced person will be able to give their insight on certain ideas and steer the project team in the right direction.