Well then, why not sit back and enjoy our labors and failures, or successes? The units I chose use some of the latest, tiny Phillips ZES LED chips, arranged in the exact location and shape as the wire filament in a halogen bulb. This is crucial, as the reflector neither knows nor cares how the light it reflects is created - only that the light emanates from the same position within the reflector.
The problem with 90% of the early LED units is that they did not use such "filament-sized" chips, and did not locate them in the proper focal plane. This caused the well-known scattered light patterns. I believe that the LED producers have done, in the more recent designs, a remarkable job of adapting current technology to reflector units designed for the now-ancient halogen technology H4 bulbs. A light unit which is purpose-built for LED illumination can do an even better job - two of the OEM LED-lighted cars that I own demonstrate this.
Most all LED 9003/H4 units allow rotation of the unit in the mount, until the best light pattern is achieved. As we see from docc's low beam pattern, it nicely replicates the halogen unit, but with greater intensity and substantially less power consumption. Hard to find fault with that. I began driving on 6V incandescent bulbs, which were about like the parking lights or DRLs on modern cars. 12V was a good improvement.
Halogen was yet another step ahead, but it is now 50+ years of age and getting rather long in the tooth. HIDs had too many limitations, such as the cost of drivers and bulbs, as well as warm-up time. Like compact fluorescent bulbs, they had their day. I see LED lighting as a 21st century parallel of Thomas Edison's 19th century perfection of the glowing wire lamp.