Steven,
You want to use servos with the best centering for the critical flight surfaces of your jet. To check this you can fabricate a servo tray and attach about a 7" long wire to the output arm. Actuate the servo and it should return to within 1/16th " at the outer arm position. The best servos should be mounted in the aileron, elevator and rudder positions. Digitals are also preferred in these positions. Save the analogs for nose gear steering, flaps and retract/brake valve actuation. Some pilots also specify digitals for flaps but ensure that there is no binding or stalling of the servo at any position- this can drain your receiver battery or cause dropouts.
I've mixed brands, with JR for the critical surfaces and HiTec for retract/brake valves. MY jet partner swears by hi-end HiTecs in his Top Gun and NATS-grade scale jets. Hope this helps.

Art ARRO