1v1F trains some IS and less JS than 1v1G. This may seem a little counter-intuitive but I like 1v1G for tall players and 1v1F for short players.
1v1G trains nearly as much JS as JS-G for taller players plus adds HA & DR. Taller players also add IS pops the quickest with IS-Center. If you don't want to train JS on your big, then 1v1 F would train the most HA & DR (more DR then HA).
1v1 F is the best way to add IS to shorter players. Shorter players get more IS pops than taller players with 1v1F. You get less IS pops than IS-Center but more overall pops with the added HA, DR, and JS. If you don't want to train IS on your guard, then 1v1G would train the most HA & DR (more DR then HA).
Hope that made sense