I'll second what other other people have said. I found Alistair at Korean Horizons pretty good. I used him as a first time teacher in Korea. He organised everything perfectly as soon as I arrived in Korea i.e. pick up, accomodation, travel etc.
I'm inclined to hold back on the praise to some degree, however. I found him great at answering the simple questions, with very prompt responses. Equally, when it came to anything which was a little more tricky, I didn't really feel that I got the responses I needed sometimes.
That said, he does come across as trustworthy and I would imagine he's a saint compared to most recruiters.