Our dive team needs lights so Im asking myself the same question. Im adamant that we need HIDs but Im hesitant to recommend any specific light given the price.
One small problem looking for dive light reviews is that HIDs are so flippin expensive not many people can afford to do a comparison. Consequently, what you end up with is a lot of testimonials. Besides, after blowing that much cash on a flashlight, its hard to conclude the one you bough isnt top notch.
That said, I dive a Sartek 18W and my wife dives an EE 10W. We like them both (big help huh?). Ive heard several complaints regarding the reliability of the EE light but havent had any trouble myself and EEs support is supposed to be quite good. The EE 10W also seems much brighter that several other 10Ws Ive seen (nothing scientific here
if my light blots out your light, mines brighter). At times the 18W seems almost too bright (a diving oxymoron I know). I never knew anemones could sense light before I got my Sartek.
I had an AUL WKPP style canister (single o-ring) that flooded on the first dive. AUL said it was probably operator error. They were probably right but they replaced the canister anyway. My wifes EE is on an AUL canister with two o-rings and has never had a problem. My conclusion: be anal about your o-rings but use a canister with two o-rings anyway. Focusable head and Goodman handle are a must. Ive also just ordered a canister and NiMH pack from stealth, Ill let you know what I think when it arrives.
There are a lot of people making lights now so the prices are coming down. Sartek, AUL and EE are tried and true but some of the newcomers (Terkle and Stealth for instance) have some good looking kits. Since no ones going to send you a loaner, try to pay attention to what others are diving and compare the spots (maybe you can goad them into a my lights brighter than yours contest.)