I never had a servo Problem within the last 6 years. I fly the following servos:

Futaba S3150
Graupner DES 707 BB MG
Hitec 5645 MG
KST X10
KST BLS825
KST DS 589

I think servos are pretty reliable nowadays. Always check them thoroughly before installing. And to give them a nice working life, program (I fly JETI) servo limit properly and take good care of servo arm to control horn ratio. Then they work less for more power.