Let's say for the sake of argument that I have a specific idea I want to play with. I want to pattern my character after Logen Ninefingers, The Bloody Nine of Joe Abercrombie's First Law books. What are my options?
Specificity by Fluff: Core Archetypes OnlyWhat we're seeing here is that you can't really have your cake and eat it too. The more you are allowed to tweak your character, the more complicated the system becomes. AD&D2e might have been the closest attempt to a compromise, but suffered from poor implementation. At the outset, it seems like 3e attempted simply to codify and integrate all of the ideas of 2e but in so doing it made them all mandatory, losing the flexibility and ease of play.
In OD&D, BECMI, Moldvay Basic and games that mimic these (Lamentations of the Flame Princess, for instance), Logen is just a fighter. My character customization options are: roll up stats, choose fighter class. This is simple, effective, and relatively fun. It's how people played for years, and stands up pretty well I think. The only problem is, if I want to play Logen as he is written, I'm either just role-playing his berzerker-rage, or the DM has to make something up for me (usually a rule stolen from another version of D&D). This is perfectly servicable, but you can't take house-rules into account for a discussion on game design.
Specificity by Diverse, Narrow Classes
In AD&D1e variants, the core classes give way to "sub classes," which become more specific. I can now play him as a berzerker class if I wanted, and that does give me more specificity and preserves the ease of learning / ease of play, but it still constrains my customization options to being stats+class (though AD&D generally gives me the option of race as well). Some people play this level with weapon proficiencies as well, which can be nice. The real rub here is that now his berzerkergang thing is the defining feature of his character, which can be a bit confusing when faced with the question of "why can't he do the things normal soldiers can do?" (after all, he has to lose something in order to avoid simply being better than the fighter.) What I gain in specificity, I lose in flexibility.
Specificity by Layering rules: Kits, Skills, and Powers
AD&D2e seems to have made an honest attempt to address all of this by introducing the much loathed Skills & Powers book, as well as making Non Weapon Proficiencies part of the core book. If that wasn't enough they also have the Complete Guides around for me to choose class kits, in addition to my pre-existing ability to choose sub-classes. Honestly, this all sounds pretty good in theory: I can now roll stats, choose class (or subclass) and race, choose weapon and non weapon proficiencies, fiddle with Skills and Powers, and tinker with all of the above via the class kits. In practice though, this can become a tangled mess. The various sub-systems don't interact well with each other, the implementation of kits is clumsy and notoriously unbalanced. On the bright side, it does address my original problem: Logen can now be a fighter with the berzerker kit and not feel like he's pidgeon-holed himself. On the down-side, it is an absolute crapshoot to deal with. The redeeming factor here however may be that all this clutter is optional. The new player sitting down for the first time can more or less roll up a dude without having to learn much of anythign about the system up front, just like in B/x.
Specificity by Integrated Abilities
D20 takes all of the above and integrates it into a unified system. For a lot of people, this was awesome. All of the customization options of 2e, but inherently meant to work together (and thus theoretically balanced). I'll not get into how well that succeeds. I never was much of a fan of the setup, but it does allow me an incredible amount of control over exactly what kind of character I want to build. The rub here is that for me to have all of those choices as a standard, non-optional part of the game as written, I need to read all of that and understand all of that. The first time player needs to read all of their class skills, all of their class abilities, all of their available feats and what those feats require as prerequisits and coordinate all of this so they can make sure they can get what they want down the line. Gone is the "roll up a character and go," but you do have more direct input over your character.
Specificity by Classless Point Buy
This doesn't apply to D&D, but it's the obvious other extreme counter-point to b/x. Abandon classes entirely, and make all skills and special abilities available on a customizable point-buy. It is the ultimate amount of customization, but also the most complicated player buy-in.
The ideal system (for me, at least) would be one that featured some kind of escalating complexity. First level characters can start somewhat broad, but as they develop and earn experience points, they have some way of becoming more specified if they so choose. In a game like this, I want players to be able to get started as easily as possible. The less player buy-in required, the more likely you are to make things get going. Once everyone is moving forward, they can dip into the more advanced rules at their own leisure.
I'm kicking around some ideas on how to best make this happen, but I'm not willing to commit them to paper just yet.