I have lived and worked as an English Teacher in Korea for several years now, and during that time, I worked with various recruiters. 
From my experience, Appletree Recruiting is the most professional of them all, and I strongly recommend them. 
Appletree Recruiting really makes a big effort to place you in a school and a community that offers all the things you're seeking, and they pay a lot of attention to detail. 

Not only was Appletree Recruiting helpful in securing employment in a particular city I wanted, but they were helpful even after my arrival in Korea. 
They do a lot to make their teachers feel welcomed.  I remember how I was presented with a gift basket by Appletree Recruiting which contained all sorts of useful guidebooks and other material for a newcomer to the country upon my arrival at the airport, and I really like that Appletree Recruiting occasionally organizes some parties and social gatherings for all of their teachers. 

 An employee from Appletree even visited me at my school several weeks after my arrival to make sure that everything turned out alright.  They have been very supportive from the start...