If I can get close enough (usually at or under 100 yards) and if conditions permit, such as no strong winds and the animals are relaxed and not twitchy (preferable grazing), and if I can get into my usual position of flat on the ground off a bipod, I will take a head shot. But head shots can be a low percentage shot if you can't place the bullet perfectly and the chances of creating a "fatal later" wound can be high if conditions aren't perfect. When the conditions are right I love head shots as they are instantly fatal and while they may kick up a fuss, they are dead and the lights are off! I've never had to follow after a head shot critter and of course, you don't ruin any meat! I like to place the bullet just behind the ear and destroy as much of the brain and brain stem as possible.
However, if the animals are nervous, alert and moving their heads around a lot, there's a big angle to deal with or strong winds - and if there's no cover with which I can get close, head shots are off the table. There's always the possibility of snapping off an antler as well, so if you're after a wall mount, head shots are not advised.
Cheers,
crkckr