If it was my team I'd play the 9 GS 10 OD.
As it stands now the difference in 10 OD and 12 OD isn't terribly large, but the GS acts as a performance multiplier. So a 9 GS with 10 OD can play like a 12, or 13 OD player at 7 GS.
That's why NT's use GS as their #1 decider on who starts, and who does not. Take the example below.
Player A: 17 JS 11 JR 19 OD 14 Han/Drv/Pas---7 GS
Player B: 19 JS 11 JR 17 OD 14 Han/Drv/Pas---9GS
On a game with both at 7 GS you could probably not decipher the better player, but in this example Player B's 9 GS makes it so he's more like a 20+ JS 12 JR 19 OD 16 Han/Drv/Pas, and Player A's 7 GS doesn't increase his in game skills like a 9 GS would.
The in game numbers I listed are not accurate, just used for example purpose, but the point made is true