There are so many good ones coming onto the market now, a plethora of choice.
Some of these use a single high-output Cree LED, while others rely on a cluster of high-output LEDs. Of course, the bigger the cluster, the brighter the lamp, but there is also the consideration of the accrued size of the front glass.
The Seac-sub Luce, a little lamp from Italy, uses three LEDs crammed together, and I suppose this is the limit when it comes to stowing it away and forgetting it until the time comes to use it. The lamp doesnt weigh too much either, thanks to its polycarbonate body.

Power Source
I am always happiest when I travel to find that all my electrical stuff uses the same size of batteries, and AA batteries are the size on which I have settled for my underwater flashguns.
The Luce (pronounced like Lucy) LED uses a cluster of five AA batteries held in a chassis that is inserted into the main body of the lamp.
The screw-down front end encloses the electronics and lamp-head and uses two O-rings to stop the battery-compartment flooding. A 10-hour burntime ensures that one set of batteries will last for a weeks night diving.

Light Source
The three LEDs are each mounted in their own reflectors behind the front glass of the lamp, and well-protected against accidental knocks by a rubber surround. I am told that they are connected in such a way that if one were to fail the others would continue working, but I had no way of confirming that.

Some lamps are switched on by screwing the head down to make contact. This system is OK, but you need to go into the water with the lamp turned on, and turn it off again only after you have exited.
Problems arise only if you use a lamp of this type as a back-up. You either find that you unscrewed it too far the last time you used it, and flooded it, or you screwed it too tight and, under the increasing pressure of depth, it turned on un-noticed in your pocket, depleting the batteries in the process.
Either way, the lamp ends up not working when you need it to.
The Seac Luce LED has a proper swivelling mechanical switch, albeit of a very simple type, so you are sure that it is either on or off. The little détente for keeping it in the off position is not very efficient, but I had no problem with it switching on when I didnt want it to.

As expected, this lamp gave a very useful output of light that was delivered in a nicely diffused cone. It was not a penetrating spot, but it was ideal as a night-diving light, and for those times during the day when I needed to pull it out to look into some hole or crevice.
It didnt prove so bright that it became embarrassing by turning a night-dive into
a day-dive. Its an ideal lamp to stow in your BC pocket ready to do the job should you
need it - which is where we came in!

Comparable Lamps to Consider
UK SL4 LED, £65

BURNTIME 10 hours
SWITCH Mechanical
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