There is tonnes of information on LED Headlamps on this site:
https://www.candlepowerforums.com/vb/forumdisplay.php?6-Headlamps
Anything that uses AA and AAA batteries is going to give you nowhere near as much light output as the new generation of headlights based on Lithium Ion batteries.
I have a Zebralight H600FW Mk III and a Mk IV. The output on the Mk IV is an insane 1616 lumens. When you compare that to the Led Lenser (approx 200lumens) and the Black Diamond (300 lumens) you can see the difference the Li-Ion batteries make. Plus they are lighter.
The trade off is you need a special charger, they get hot though, and they only run for about an hour on the highest setting, but I always carry a few spare batteries so I can detect for a few hours at night on the highest setting. They are fully programmable so you can trade off brightness for battery life. On the highest setting it's like having a portable sun strapped to your head.
The latest generation of head torches are High CRI which gives the light a more natural colour like natural daylight.
You will also need to decide if you want a floody or spot beam or a combination of the two. Floody is best for night detecting because of the wider beam angle and even lighting (no bright spots).
The cheap eBay versions will do the job but will have nowhere near the claimed Lumen output. They can be poorly made and use lower grade LEDs. Some of these cheap eBay headlamps claim as much as 6000 lumens light output which would be enough to set your head on fire. The actual lumen output is probably closer to 600lm.
A good high discharge 18650 battery costs about $20 and a good digital charger about $50.
Last year for Christmas I got my 2 cousins an Armytek Wizard Pro v3's each and they were very good, they were on special for around $150 each and came with a battery and magnetic USB charging cable included. On the highest setting they were blindingly bright(1800 lumens) but would only run for a few minutes before they got too hot and auto switched to a lower setting.
Anyhow I can highly recommend the Zebralight, they use them for things like sperlunking, jungle trekking, and mines Search and Rescue.