On other hand, 2nd choice at least has good CPU, supposedly.
So on that, adding more ram and different (read better) GPU could get things done.
Downside is that Original poster didn't mention what kind of computers these were. If they are laptops, replacing GPU is near impossible. If desktops, I would also suspect that the PSU is weak and wont be capable of feeding decent enough GPU for Farcry4
All in all, It is quite likely that for same amount of money, better (It is quite likely that if par is still FC4, the price point will be higher than the computers listed) parts list can be given.