Never has the old engineering statement of "good - cheap - quick ... pick any two only" been more applicable than it is for RC steering servos!!
You seriously get what you pay for in terms of centering, consistency and of course reliability.
I run Futaba BLS551 in all my cars with a Futaba 9550 as a spare (which I never need, probably telling me I need another car to put it in
)
http://www.jemodels.com/nitro-models...facturer_id=35
I still have my old Futaba 9401 from about 1988 in my touring car, as far as I can remember it's never had a gear set fitted, that is reliability and value for money IMHO
Cheap no, highest quality yes but value for money is brilliant, you can spend a lot more but not get any real improvement!
The Power HD servos are also excellent and when I need another servo it might well be one of those.