Your going to get every answer in the book on this. I'd use the search function and you'll be able to pull up many different topics on this. The largest diameter broadhead is usually not the best broadhead to use. You have to match the broadhead with you bow, draw weight, size of the animal etc. Personally I use the Slick Trick Magnum. I don't measure my broadheads by diameter though, I'm more interested in the amount of cutting surface. With my slick tricks I have over 2" in cutting surface and don't have to worry about any mechanical error with an expandable opening up. I'm not saying expandables are bad, I just prefer fixed blade.