The three things to consider when choosing a broad head are how the weight will effect the spine, how it will effect the FOC and what the cutting diameter will be.

The lighter the head the stiffer the arrow will be, the less FOC you will have and normally you will have less cutting diameter. I really wouldn't suggest heads lighter than 100 grns to anyone unless they were shooting a very light set up. Like a short draw length with short light arrows. The smaller cutting diameter will help slightly with penetration issues. Say for women and kids or really small guys like myself.

If you are shooting more that 26 inches of draw length and more than 50 lbs of draw weight I would suggest you look at broad heads in the 100-125 grn weight range, maybe heavier in some cases.

My opinions anyway.

Paul