How To Divide up the Primary Stats?

Of all the pieces that make up an RPG, how one divides up stats, is probably the most fundamental. They affect everything from the power of abilities, to chances to hit, to whether or not the character gets some.

Character stats are also fundamental because from the most basics, (Strength, Dexeterity etc) one can automatically derive the other more secondary stats (Hit points, "saving throws," speed).

The challenge is to do the following things: 1)Divide the stats in a believable way because this contributes to immersion 2) Make the stats simple enough that they can be easily understood and adjusted because players want good gameplay 3) Bear in mind how the stats will affect spells and abilities in context of combat.

I submit here, for judgment of all of you, two paradigms of stats. The first is the familiar AD&D 2.0 that all of you are all probably familiar with:
Strength
Dexterity
Constitution
Intelligence
Wisdom
Charisma

This paradigm is familiar to all who have ever played an RPG. It is easy to adjust, to manage, and everyone will automatically assume which classes need what. There is no need to re-invent the wheel if the wheel is rolling just fine. There are however, two problems I see.

The first, is that there is no character stat for visual perception. If a hunter fires a bow, a thief spots a trap, or someone finds a secret door which stat best provides the bonus? Dexterity might work for the fist example, but what do you use for the other two? Wisdom maybe?

Secondly in covering "Wisdom" I have always thought that it covers to much. If I say, use wisdom to cover visual perception, it seems strange that I also use it to cover the resistance to a charm spell, the cleverness of a problem solving, or a the sheer will power to haggle for the right price. I have always thought that wisdom was a "catch all" for mental powers not included in intelligence.

There then, are two problems I see with the AD&D paradigm.

The second Paradigm comes from the game Arcanum. Arcanum has eight stats instead of six. There are four "physical stats" and four corresponding "mental stats." Here they are:
Physical Stats / Mental stats
Strength / Intelligence
Constitution / Will Power
Dexterity / Perception
Beauty / Charisma

I'm sure you can see some of the advantages to this paradigm. First, there is a visual perception stat. Secondly, even Beauty and Charisma are rightly divided. How often did you play a table top RPG and wonder if your character was attractive instead of just charismatic? If I were to ever table-top RPG again, I would want to play in a system that used these stats rather than AD&D stats.

There is perhaps a not so obvious down turn. Arcanum was a radically open world design. It was so "open" that there were not even character class. Your avatar became what you allotted the skill points to. This was great for creating original, unique, characters in a solo-RPG -and it would be a nightmare for PVP balance. Also, I can imagine how Charimsa might affect abilities (Paladin auras, for instance) but I see no place at all for physical beauty.

There are other paradigms out there. World of Warcraft, has its own workable paradigm. As do many other games. What must be decided here is what kind of paradigm would be best used in this game. Keep in mind that if this picked well, than all other stats can be derived from whatever primary stats are chosen.

That will keep it simple for players, as well as provide believable immersion.