Depending on the projectile & charge weight you use one may give better accuracy in your particular rifle than the other. I always try both when working up a load for a rifle. Max loads with 3f are lower weight than 2f, so load accordingly.
Two will give a little slower velocity charge for charge. You have to up your charge around ten-twenty percent to get the same velocity. So seventy of three about equals eighty of two. Three is a little more economical to shoot.
Howsomever a 1600 fps load in two f produces lower breech pressure