Julga has more potential, way better B-skills and is as good as Batts in the main skills. But he is one year older. I'd say train neither of them and try to get three new trainees. Or, train both of them with one additional 18yo who has some potential as opposed to Batts. And if it's really got to be only one guy, take Julga; Batts will reach his potential very very soon when trainedd as a big, and he'll be incredibly one-dimensional.
Also, what did you do to get their Game Shape down so low so early in the season?