TowerPro servos from the Taiwan TowerPro factory.Tested on the workbench. Strong with medium speed and v.g. centering.That was two years ago. Nothing fancy about Towerpro servos but these ones come from the factory. They cost me around $90. You can buy them from Bangood or Aliexpress for as cheap as $20 but what you get will not perform to these specs:

Specification:

Operating Voltage: 4.8v-6.6v
Stall Torque (4.8v): 15.0kg.cm
Stall Torque (6.0v): 18.0kg.cm
Servo case: Alloy case in the middle
Gear Type: Metal gear
Bearing: Double ball bearing
Temperature range: 0- 55deg
Operating Temperature Range: -20 ~ +60 Degree C
Operating Speed (4.8v): 0.18sec/60 degree
Operating Speed (6.0v): 0.15sec/60 degree
servo wire length: 32cm