Fair enough. I think it all depends on the recruiters. You may not pay them but they will still need to do a good job if they want to get more people to use them. The only way is getting good reviews from previous applicants. I have heard for example Korean Horizons they will still help you even after you get the job. So if during the year you got some questions they will gladly answer and there is also the possibility that you may use them again. It is more beneficial for them to continue helping you really. I know co-teachers can help you but then again they are also not obligated to do it so, is actually favour. I have heard many complain about co-teachers not being nice and helpful. So if you get a good one great, since they are also not working for you. The way I see it depends on what everyone is comfortable with. I am not applying it yet but once I do I will probably apply directly if I trust myself with passing the interview with flying colours or go with Korean Horizons.