My personal choice is fixed, cut on contact. There are some good mechanicals out there for sure, and if you have enough KE, and your bow is tuned correctly, you should be fine. I just like the fact that I have less of a chance of broadhead failure with fixed.
Also, IMO the most common reason folks go to mechanicals seems to be because they say " fixed blades won' t fly out of my setup" . That is crap. A poorly tuned bow is a poorly tuned bow...period. Switching to a mech head for that reason results in putting a " bandaid" on the problem.
A properly tuned bow should have no problem shooting either. Do this first, then decide on what you want to shoot.