Its hard to compare Luxeons with 1 or more CR123 (Longbow) to a variety of batteries powering 5mm LEDs (Peak). The Longbows will always be much brighter, but the Peaks will enjoy much longer runtimes.
From prior reading/research, I got the impression that both brands were reasonably respected. Longbow seems to be sort of mid to high-mid in the range. Not quite the level of Surefire, and well short of custom lights like the Alephs. When I made my purcahse, I went with the QIII and saved about $20 (which, incidently, went towards buying a Peak Shasta). The Longbow's HA-3 finish would probably last longer, but the lower price of the QIII was more attractive in the short term.
Maybe when Peak releases the Luxeons they have been talking about this comparison can have more meat to it. Right now it really is apples and pears. We can compare the color and thickness of the skin, but not the insides so much.