Exposure (and thus skin tones) are different in all three, the 3rd one also has a significant color difference from the first two, but I think it has the best skin tones.
As mention, try to avoid lighting from below, unless you specifically wan that look...often called 'Monster Lighting'.
They strike me as a bit wide for 'head shots'. These are head and shoulder shots...and something like this could cost him a job, or at least a chance for a job.
For actors, head shots can be just as or more important than their resume. So if you imagine a casting director sitting at a desk with a huge stack of resumes and head shots...he has to cull the list and a head shot that doesn't meet the 'preferred standard' may get tossed out simple for that reason. Now of course, both photography and acting are creative fields, so trying to show some originality isn't always a bad thing...but you have to be really careful with that because you have to get past the first few barriers before your creativity might be appreciated.
In other words, look up a whole bunch of good head shots...and try to do something along those lines.