Lux is a more meaningful measurement (in as much as you can sum any of this up in a single number), but it assumes a specified aim, and is generally only used by the German manufacturers following the StVZO requirements. Lumens are simpler to calculate, and are generally bigger numbers, so tend to be the headline figures that most manufacturers use (in a manner comparable to cameras and megapixels, where the performance of the attached optics are disregarded).
Pragmatically, the best way to compare lights is by riding on an unlit road with someone who's got one. Failing that, decent photos of beam shape like those at
http://www.peterwhitecycles.com/headlights.phpFeatures other than performance are somewhat easier to compare, though it's always hard to judge reliability. I'll generally trust the opinions of audaxers and all-weather commuters who say a given light is reliable, but selection bias makes it hard to draw conclusions (other than probable failure modes) from negative reviews.
As for specific recommendations, I'll second sojournermike on the Cyo Premium series. It's a substantial LED/optics upgrade on the non-premium Cyo, which is a proven design. It probably represents the best price:performance ratio.
I also have the IQ-X, and while it certainly gives you more light than the Cyo Premium, it's a lot more expensive. For me, the killer feature is a beam wide enough that you can safely ride recumbents round tight corners with. There's a known switch problem with the IQ-X, though so far this seems to be a fault that's sometimes present from new, rather than one which develops over time. Otherwise, it's still a bit new so hard to judge long-term reliability. I think the IQ-X's double-articulated plastic bracket is stupid (unless you're trying to weasel round a rim brake), and have used the much simpler Cyo bracket on mine.
Hard for me to justify the cost of the Schmidt stuff over the equivalent B&M for something that - no matter how well-engineered - is likely to fall victim to Moore's Law. Your shiny things budget may vary.