When it comes to Character Creation and Progression, I like to keep two things in mind: style and personality. The thing I find great in games, Multi-player in particular, is individualism. Making a character that represents you and your play style, makes the experience that much more meaningful.
So with Style, I'm obviously referring to the appearance of the character. I've found that the most depth in the customization options there are, the larger a player's creativity can shine on. All Points Bulletin, that 'GTA MMO' as most would call it, has possibly one of the best Character Creation systems I've ever seen in any game. The deformers and texture detail are mostly done in dual axis sliders and the number of textures for each part of the face make for a great starting point. There are also added details that can be placed through UV projection such as custom tattoos or scars that can be placed almost anywhere on the body. With the ability to create custom fashion as well(I.E. added textures and logos to clothing/ equipment) players can create their own style that is practically impossible to replicate with matching gear unless traded.
Now for Personality, I'm speaking on the play-style and skill sets of the character rather than a literal standpoint. When you can choose the way your character progresses, It adds immersion into the game world for the individual whether it would be a player who specializes in ranged weaponry or someone who will try to be a jack of all trades, it's all about freedom. Having basic frameworks is nice for those who just don't want to sit and work out the numbers or spend hours planning out, but also having the option of a bare bones "Custom" character class adds to creativity in a way. Make it simple for the general audience to be able to pick up and play nicely, but allow room for the more hardcore players to tinker and experiment to find their niche set up.
Missing an eye, scars, etc options then offer you bonuses to an intimidation factor with a wide range of NPCs, but may negatively harm your ability to interact with others.
This is a great point to also consider. I actually have a concept in mind of a race created from human volunteers, ends up facing higher prices at stores and general distaste from from Pro-human NPCs. Applying ratings to visible features that influence NPC reaction or behaviors would add to the depth of a game world. So if you have a ton of scars, war-torn complexion, and a blank eye, NPCs would be wary of you, show defensive posture and reveal tells of intimidation when you communicate with them. But if you decided to be a handsome, charming looking fellow, that would make NPC characters seem more comfortable and find you easier to trust. And for the sake of humor, maybe if you make yourself look totally ridiculous, NPCs will hardly take you seriously and possibly make snide remarks. If I had the time and knew of a Programmer who would put the extra time in, I'd probably want something like that in a game. Maybe we'll see something like that out there!