Because I build from plans I have gotten into the habit of having my planes assembled in the bones, {without covering} then setting the plane on the CG machine and just taping the servos and gear on the outside of the plane until I get it close to the CG. Then I hard mount the gear close to those areas inside the plane. That gets me close enough so just moving the battery pack will get the CG set. Gear selection depends on too many things to give a blanket statement. Size, weight and type of flying dictate a lot.