All servos are not created equal. Their is a big difference between analog and digital servos, digital being a better servo. The major brands such as JR Futaba and the digital Hitec servos all do a good job. I would stay clear of off brand names or the really cheap servos. You can get Lower end JR digital servos for around 38 bucks a piece. Not a bad price for piece of mind. I have used cheap servos before and yes they do work, but they never seem to center themselves ever time. Makes a guy wonder why he is alwayts trimming his plane. Let clarify one thing, analog and digital servos are built the exact same except for digital servos have the amplifier in them and gives you the holding power instantly were a analog does not. Their is also cored and coreless servos as well. Do your research, their are some great articles I hace read asking the question are all servos equal?