I use both, If I am hunting an area where I anticipate a longer shot, I'll use a fixed blade. If I'm hunting an area where I anticipate a short range shot, I'll use a mechanical. that's how I do it.

I always have to chuckel when I read someone blame the tip of thier arrow for lack of success. I ain't the broadheads fault if ya can't place the arrow where it is supposed to go. And most story's about mechanical broadheads not working, are really stories about a missed place arrow and the person telling the tale is expecting the broadhead to save him.
sorry ain't going to happen, a missed place arrow is a misplaced arrow and recovery will vary no matter what broadhead you were using at the time..

As for my personal experience comparing fixed to mechanical, I have noticed that the mechanical's seem to put the deer down quicker. for me a good shot with a mechanical the deer is usually down 30 to 50 yards from me. when I use a fixed seems like the deer are usually found 70 to 125 yards away. I guess maybe because the deer is out farther when I use a fixed to begin with.
anyway that's my experience.

I think all the broadheads on the market today will put a deer down if placed correctly..