This depends on how many people you need to fit in the tent or if there are limitations on the plot size of which you are allotted to hitch your tent. If you are going to a campsite without a reservation, then it may be that there are only small spaces dotted around which you can hitch a tent. It might be easier to find 3 spaces to hitch two-man tents than 1 space to hitch a six-man tent. For hiking, it is better to have one tent between many people than many tents between many people. This is because the total weight per person would be less sharing a larger tent between more people than small tents between many people. Many people will set up one big tent quicker than many people will set up many small tents. So that one person does not take up all of the weight burdens of the tent, the weight should be shared in ways such as other group members carrying food and spare water for the tent carrier. Apart from this, a good tent size is simply the biggest you can get for your budget unless you want a warm and cozy experience.