The cockpit is not always in the "head"
Atlas cockpit is left eye, so the eye on YOUR right when he is facing you, it is very small and hard to hit.
Cat cockpit is large and easy to hit, its the windshield you see in the middle of the CT.
Awesome cockpit is retarded easy to hit, its in the massive head and has a hitbox the size of a hot air ballon. If you cant kill a awesome in 2 headshots in less than 10 seconds your hand eye coordination must be worse than a blind guy. I seriously feel bad cockpit shotting awesome in my gausscat, its literally like taking candy from a baby.
Hunch also is in the head but since the head is sunken into the top of the CT and has a very small hitbox it can be a pain to hit, luckily the RT hold most of a hunchs arsenal and is very very easy to hit and lightly armored. I almost always core them through the RT cause almost all of them fit XL engines making the RT destruction also a killshot.
Jenner head is similar in location in the middle of the CT to a cat, but much smaller and harder to hit, also almost always moving way to fast to get off a cockpit shot. But very very easy to leg, i try and leg jenners whenever possible and then just let the LRM boats finish them off since they cant avoid the LRM when they cant move.
Commando is always moving to fast to headshot, but is so lightly armored a few good hits to any location will kill them in short order.
Dragon heads are not as easy to hit as you would think, they are in the upper middle of the CT where you would expect but the protruding nose and small raised LT and RT make it hard to hit. The CT though is massive and easy to hit so i usually just try and core them straight through the CT, they usualy move too fast to make aimed shots effective anyways since they can do 100kph with even a small engine upgrade over stock.
And the poor cent, has a head which is fairly easy to hit, i would place it between the poor awesome and hunch in difficulty. However the arms on this thing are just huge and make headshots from the sides difficult. I usually blow off the weapon arm first since they are very lightly armored, then go for the headshots once the main weapon am is out of the way.