KO servos are very good - I have been running some 616 (high torque) and 617 (high speed) Blue Bird servos recently, these are good value for what they are - under 30 quid from
RC Direct and they are fast, metal geared etc etc. I am running the 617 in the Tamiya TRF 501X review car, and the 616 in my touring car.
I mention these since I am reviewing them - Some of the older bluebird servos weren't amazing, but the newer 616 & 617 are great for the money, I wouldn't review crap.