My basic sport servo for my DX7 w/ AR7000 or AR6200 is an inexpensive set of analog servos: For everything except the throttle I use Hitec HS-485HB (was the HS-475HB). Plenty of torque and speed for the 4Star. For the throttle I use an HS-425BB (standard size) or HS-85BB (mini size). If it's a bit higher performance (60-size) I'll use JR D821 digital servos.
Hitec servo connectors work just fine with the Spektrum Rx.
Check out
ServoCity for help on the details (Hitec and Futaba).
Be aware that the performance of the servo differs based on Rx battery voltage. 4.8v is slower and generates lower torque than 6.0v.
HTH,