First, for wreck penetrations, you very likely have NO need for a can light. Wreck pen dives just generally do not last long enough to need more burn time than what you get from a decent cordless light.
Second, if you get a light that takes more than one battery and they go in end-to-end then the light will be so long that it will be inconvenient to have it mounted on a soft or hard Goodman handle with the light on the back of your hand. I would highly recommend getting a light that is only 1 battery cell in length.
Third, a light that has multiple brightness settings is very handy. As someone already said, 1000 lumens is sometimes simply TOO bright. Not to mention how much longer a light will burn if you are running it on a medium or low setting.
Fourth, I have twist-on lights and don't use them anymore. Requiring use of 2 hands to turn a light on or off is too inconvenient for me. Plus, every twist-on light that I know of is also only one brightness, so combined with my preceding point, I don't use twist-on lights anymore.
Fifth, good 18650 cells are good. Good 26650 cells are even better. The only thing that might be better than that (in my opinion) would be a light that takes 3 or 4 18650 cells all arranged so they are side by side (thus, making the light fat but not long). But, the only lights I know of that have that arrangement are really TOO fat, in my opinion. And, a single 26650 will last long enough for just about any wreck pen diving - at least until you're talking about serious deco time - that there is just no need for multiple 18650 cells versus one 26650.
Sixth, lights with slide switches suck (in my opinion). It's just too easy to have one turn on by accident and not even realize it. A push button (that has some way to lock it) is the way to go, in my book.
As a result of all this, my current favorite light is the Xtar D26 Whale. They were running around USD$65 on eBay, but they may be less now that the Xtar D26 1600 is out. I have 2 of the D26 and 1 of the D26 1600. The 1600 is a better light in most regards, but the electronics controlling the 1600 are not solid yet. I and others are having issues with it reporting that the battery is low or dead even when the battery is over 90% full. Until Xtar gets that sorted out I cannot recommend the 1600. Once they do, the 1600 will be The Light to have (for a cordless dive light) in my book. It uses the latest LED tech (the Cree XHP35 emitter) which is substantially brighter than what is used in almost every other light that is mentioned in this thread. All those other lights are a nominal 1000 lumens. The D26-1600 is a nominal 1600 lumens. It is BRIGHT. With a very nice, tight spot beam.
Pair the D26 (either one) with an Oxycheq Raider light sock to mount the light on the back of your hand and you have a near-perfect setup (in my opinion).
Second, if you get a light that takes more than one battery and they go in end-to-end then the light will be so long that it will be inconvenient to have it mounted on a soft or hard Goodman handle with the light on the back of your hand. I would highly recommend getting a light that is only 1 battery cell in length.
Third, a light that has multiple brightness settings is very handy. As someone already said, 1000 lumens is sometimes simply TOO bright. Not to mention how much longer a light will burn if you are running it on a medium or low setting.
Fourth, I have twist-on lights and don't use them anymore. Requiring use of 2 hands to turn a light on or off is too inconvenient for me. Plus, every twist-on light that I know of is also only one brightness, so combined with my preceding point, I don't use twist-on lights anymore.
Fifth, good 18650 cells are good. Good 26650 cells are even better. The only thing that might be better than that (in my opinion) would be a light that takes 3 or 4 18650 cells all arranged so they are side by side (thus, making the light fat but not long). But, the only lights I know of that have that arrangement are really TOO fat, in my opinion. And, a single 26650 will last long enough for just about any wreck pen diving - at least until you're talking about serious deco time - that there is just no need for multiple 18650 cells versus one 26650.
Sixth, lights with slide switches suck (in my opinion). It's just too easy to have one turn on by accident and not even realize it. A push button (that has some way to lock it) is the way to go, in my book.
As a result of all this, my current favorite light is the Xtar D26 Whale. They were running around USD$65 on eBay, but they may be less now that the Xtar D26 1600 is out. I have 2 of the D26 and 1 of the D26 1600. The 1600 is a better light in most regards, but the electronics controlling the 1600 are not solid yet. I and others are having issues with it reporting that the battery is low or dead even when the battery is over 90% full. Until Xtar gets that sorted out I cannot recommend the 1600. Once they do, the 1600 will be The Light to have (for a cordless dive light) in my book. It uses the latest LED tech (the Cree XHP35 emitter) which is substantially brighter than what is used in almost every other light that is mentioned in this thread. All those other lights are a nominal 1000 lumens. The D26-1600 is a nominal 1600 lumens. It is BRIGHT. With a very nice, tight spot beam.
Pair the D26 (either one) with an Oxycheq Raider light sock to mount the light on the back of your hand and you have a near-perfect setup (in my opinion).