Its all about personal preference. If you want a gun that is softer on paint go with the rail. if you want a gun that you can shoot more paint with before having to fill up go with the gog. The guns are not much different from each other. Go to your local field and hold them both. get the feeling of each gun in your hand and see if you can shoot them. Pick the gun that fits you the best.
also my vote goes towards the rail hope this helps