There is tons of good info regarding mostly HID on this website, but they also have good deal of info relating to standard halogen lights.

http://faq.auto.light.tripod.com/

An excerpt regarding APC and generic projectors:

APC headlights, quality and price
APC makes headlights for several trendy automobiles. When mounted, they look really great. Unfortunatly, the build quality and function quality is not as high as OEM. Which makes sense, most of them are cheaper than OEM. In addition, they are made in smaller quanteties than OEM, and should call for lower margin. You may wonder, how they actually conform to DOT standards? Well, the minimum requirements of the DOT standard is not very hard to accomplish. But to satisfy todays demanding customers who have been looking at $1500+ BMW headlights, well thats a hole different ballgame. Unfortunatly, very few people would be willing to pay that much. So they have found their niche in the "good looking" segment, and they do it well. What you should know is that the projector unit is made of thick cast steel, with relatively uneven reflective surface, compared to projectors from Hella. Most APC headlights until 2002 utilizes the same projector unit carrying a H3 bulb. H3 bulbs are mostly used in fog lights and thats excatly how the beam looks like. A wide cloud relatively close to the front of the car. Please dont even consider putting overwattge or HID in them. New for 2002 is use of 9005/9006. It has been seen in 88-91 Civic/CRX headlights. Beam pattern is not reported better. Reflector was partially dirty on arrival.

What is the quality of other, almost generic type headlamps?
Ebay and many other internet stores are filled with low quality headlamps of all kinds of origin. Examples of this are Matrix, Diamondback, Denji etc etc... What they all share is that they are low priced. Some sealed beam H4 Diamondbacks can be had for $30. If a headlamp is cheaper than OEM, be sceptical! Remember that to make a world class headlamp, very advanced CAD/CAM equipment is needed in addition to qualified engieneers. You have to ask the question: Will $30 cover this cost? $30 is way to little. You have to double it.
All headlamps should minimum comply to either DOT, SAE or ECE. Not that it takes much to comply to SAE regulations, but its better than nothing. Be aware that there are smart sales people out there: Examples of advertised product having the SAE label, but what you get in the mail does not have any labels. Conclusion to this is to: Buy brand name products that has an organisation that stands behind the product. Brand names are typically OEM prouducers as well.