It's really just a matter of "best servo you can afford". I think it's worth it to go with the 425 servo on elevator and rudder if nothing else. Throttle, the 311 or 322 or whatever is fine. But if you can only afford the less expensive 3xx series, you will be fine, you'll just get better performance and life out of the 425 or better servos.

Of course, no matter how good the servo, if your pushrods aren't right, it just doesn't matter.