I looked at the hobby king retracts but I am huge fan of the Eflite based on their toughness. I had a gear down crash landing in which I landed flat very hard. The wheels sprang back and left skid marks on the underside of the wing being fully compressed back. The nose gear servo was damaged but all three of the retracts worked great. The other advantage of the Eflites is they sense an obstruction and shutdown. There are plenty of video on youtube of installers damaging the linkage of their retracts when installing the system and the wheels get hung up or smashed while the openings are refined. That is my 2 cents.
You can also look at:
http://www.sonicelectric.com/Merchant2/merchant.mvc?