I thought I would add some "insider" info to the above. I walked thru analyze, dismantle and build source code for current server build and here are my finds, in addition to the stuff listed above:
Jenquais get extra bonus to analyze chance. It is hard to tell what the exact amount is since the formula is pretty complicated and draws from characters stats, but it is sizable.
Terrans get extra bonus to build quality. Again, it is not obvious what it is, the formula is pretty complicated.
Progens get extra bonus to dismantle skill, you have higher chance to get each component. At least here it is obvious what it is and it is flat 20%.
Also, I couldn't find anything that would indicate that amount of formulas would affect build quality, so I have to provisionally disagree on that one
Knowing the above, you'd probably want to have Jenq character build uber rare items since they have the most chance to analyze these successfully. You don't want to fail analyzing these L9 scales.
Common place items, use Terran. You will get consistently better results when building.