There are lists of Top Brokers By Volume floating around showing the most popular brokers. Does broker volume affect trading at all? I would think that maybe brokers with higher volume would have less slippage with large orders due to having more people to pair too. Am I misunderstanding how that works? If that is indeed the case, would market makers suffer less from this than ECNs due to them taking the other side of your orders instead of matching you to others?