Sadly this is a bad image because some of the hunters were rotating away from their model, so the first two hitrays look like they hit thin air.

You want to look at the enemy's chest with melee weapons, because it's a bigger target. Once a melee hitray has hit something, it will not hit anything else - but the thing it hit is ignored when processing further rays from the same swing. Looking at the chest means your hitrays are less likely to fall in between the heads of the commons.

Crouching is best because you can have the ray extend the full 70 units forward by looking straight ahead, while still attacking the chest area, and your teammates can still shoot over you. If you look down, the actual linear distance that the ray travels away from you (as projected on the ground) will be reduced. Because trigonometry.

So is crouching better, or are there other variables involved?