I have a Princeton Tec League 100. It's not a great light but a pretty good one especially at the price. Ergonomics, runtime and brightness are all pretty good. Works fine for me in the cold and murky Atlantic at 135 feet. $50 bucks is hard to beat.
If I were willing to spend more money on a dedicated dive light I'd be looking at Light & Motion, particularly the new GoBe lights.
Ive got a Ledlenser Frogman I use while spearfishing. Not powerful enough for nightdives, but I've used it on nighttime dives nevertheless. Its good for peeking under rocks and other dark places during the day and the yellow color is highly visible should you drop it. Didn't cost a fortune either.
Exsopsure lights are good if you have the money, UK company, there known for bike light but recently started marine lighting to, typically there built in battery but very bright and good runtimes.
I dont know any other dive light so could not compere them to other or further comment unforantly, but I will say there bike lights are very very good if you can cough up coinage, I personly cant but half my cycling club can. and I have seen just how good they are!