Bottom line is you want to be able to get a device that supports 2.4 and 5ghz at the same time, that way you have more available slots to the users as far as frequency is concerned, as well as the ability for a user to move frequency if one is noisy. If I had to pick one it would be 5ghz most of the time, but there are instances where 2.4 is the better choice plus some devices dont support 5ghz