It depends on the drilling you're using. The ending top weight, along with the correct ratio of side and finger, will determine/enhance how your ball reacts.
For off label leverage type drillings, higher starting top weights will generally give you a stronger backend reaction. If the top weight is too low to start, you may end up with bottom weight and the ball may roll out and lose carry.
If the top weight is too high for a plain label drill, the ball may roll too long and not finish properly on the backend.
So, for off label leverage drillings, use higher top, between 3.5 - 4.5. For label drillings, use lower top, between 2.5 - 3.5. =:^D