AC bonuses are as follows, based on Untyped bonuses:
Dodge: 4:1
Enhancement: 2:1
Sacred (or Profane): 3:1
Natural Armor: 2:1
Deflection: 3:1
Armor: 2:1
Shield: 3:1
Insight: 4:1
Am I missing something?
I don't get this. Shield, Natural and Armour don't go into touch AC, which degrades their value. But all three can be enhanced with individual enhancement bonuses. Deflection, Sacred/Profane and Insight always work against everything, unless they are "an xxxx bonus to Shield AC" for instance. They are clearly more valuable. Enhancement is the least valuable - it's only good because you can enhance so many things with it (AC, Armor, Shield, Natural).
So I think you've got all the ratios the wrong way around. One point of un-typed is worth two points of Insight or Sacred/Profane or four points of enhancement, etc.
Its that Shield, Armor, and Natural bonuses to AC are somewhat easier to come by, thus worth less when converted to another bonus type. Remember that my little guide is changing the bonus listed before the ratio into an untyped bonus. Thus, 2 points of natural armor are worth a +1 untyped bonus to AC, and vice versa.
As to the Sacred or Profane, those are somewhat easy to find (just look in CC for a list of decent choices). They usually have a reqirement attached, such as a code of conduct, which makes them worth a little less because it is easier to lose them. Whereas Armor and Shield bonuses can be taken outright, one wrong step and you are denied your Sacred or Profane bonus until you recieve an Attonement spell.
Basically, the chart is based on how common the bonuses show themselves. Dodge bonuses are in a number of sources. Enhancements are easily obtained, but there is a limit to them. Very little can boost a Deflection bonus, and because it is more potent than most bonuses it is harder to convert into an untyped bonus.
But if you go the other way (Untyped to typed) the chart doesn't actually reverse. I need time to work it out, but the process of going from untyped to typed should be more accurate.