The one on the left is 2nd place to me the shoulders she has look wicked plus her knee and elbow pads look the most realist but the far right one takes the cake for me because of the hood and hair cut makes me wish that design was in Mass Effect
I am running a 4th edition Sci fi role playing game and these will make great visual aids, their awesome your a super artist ever submitted your work for role playing books? This guy over here [link] has some awesome stuff he is working on.
N and B are the only ones, to memory, that were given mention in Mass Effect, though fans have come up with an A to Z compilation of the codes, in this instance K = Naval Warfare - Specialists in space tactics for combat between ships, knowledge of ship weapon and operating systems, their limits, and when they can be broken. Mainly larger "fleet" vessels.
But that's just a fan made literation. B = Infantry and N = Special Forces (canon) /MEnerd
While the head is a tad bit big I don't think thats anything major. And as to someone commenting on the jaw, NO, don't change it because sometimes women have masculine aspects and sometimes men have feminine aspects. This could just be a trait of the character.