Fixed. And only Fixed. Too me, mechanicals are just one more thing that can and do go wrong. The only benefit I can see with mech.s are they may be easier to tune than some fixed blades because they fly more like field points. there are alot of fixed blades that will shoot comparatively to mech.s under most circumstances.
I am basing all of this on direct experiences with these by myself and the people I hunt with. Now for people with very fast bows, carbon arrows with short straight fletch, etc. ,,, Mechanicals may be the only broadhead for the setup.
I have a friend that swears by them but he shoots the fastest, lightest, setup in our
group and no fixed blade would fly right with his 3 inch straight fletching. Each to his own. I' ll stick with my MUZZYS.[:-]