Lots of people love Black Diamond, and they are definitely great lights.
I like Zebralight 18650 headlamps due to their capacity and max/min brightness. ZL H600d MkIV 18650 High-CRI is a really bright 1600 lumens on high and is high CRI, so colors appear more natural. Low is so low you preserve your night vision (even though not a red LED) and lasts from 17 days to 5 months, depending on how you configure it. High lasts up to 5 hours (stepping down to about 300 lumens after a few minutes; medium lasts 13 hours to 7 days.
It's programmable over three presets with 12 brightness levels available for each preset. Weight is 1.4 oz empty, 3 oz with battery, and 4.2 oz including the headstrap. Contrast this with the Black Diamond Icon 500, which has about the same amount of energy capacity. It's 10.6 oz, 2/3 of a pound on your head, and puts out 1/3 the lumens of the Zebralight. Petzl TacTikka+ is 3 ounces, but energy capacity is half for non-rechargeable batteries and less than 1/3 energy capacity using rechargeable batteries. Max brightness is about 20% of the Zebralight. You aren't likely to find a lighter, more efficient light in this battery configuration than the Zebralight.
18650 cells can pack over 3500 amp hours (10 watt hours or about equal to 4 rechargeable AAs) , don't leak, and are available all over the place (especially since the rise of vaping). I like the ZL because they are very robust, efficient, super compact/lightweight, and have awesomely low moonlight modes. Lots of choices on beam shape as well. No red led is a drawback, but the low setting is so low it helps maintain night vision. Pros outweigh cons for my needs.