I like both but I shoot fixed for 90% of my hunting! I generally like a good solid 3 blade head with ultra sharp blades & a super hard tip. I have found this type of setup works on any type of game animal! The 2 heads I like the best are the Rocky Mountain Ti series & the Ironhead 125's. IF I use a mechanical I use a Gator XP for the really big cut (works great on turkey's and coyotes). I also really like the Snyper.

This is kind of my guideline for the type of head I would use based on the animal being hunted and a bow generating between 65 & 70lbs of KE.

Turkey - Mechanical with a massive cutting diameter.

Deer & Black Bear - 3 or 4 fixed blade head (Rocky Mountain TI-110, Thunderhead, Muzzy are all examples of this style of head) or 2 blade mechanical (Gator XP or Snyper) with a moderate cutting diameter. For Bear a wider cut is important in my opinion (TI-125 a good example).

Elk, Caribou - 3 or 4 fixed blade head or a moderate cutting diameter mechanical with rear slidding blades for extra penetration (I personally would not use a mechanical), a cut on contact head is a great option as well (Magnus, Phantoms, Bear Razorhead, Rocky Mountain Tradition are all good examples of this style of head).

Moose - 3 or 4 blade fixed blade head or a cut on impact head. I would not use any type mechanical on this size of game.

I think too many people get caught up in it's either a mechanical or a fixed....I tend to think it's a matter of choosing a good broadhead design for the type of game you are hunting. If you only hunt deer & turkey a mechanical can be a great broadhead as well as a good fixed blade head. Both will work & both have proven they will work. If you are only a moose hunter then a mechanical may not be a good choice. Why not use more than one style of broadhead?