I first tried the ND3 by BSA. Bad move.
Next I got the Elusive Wildlife Technologies XLR 250 Kill light.
http://www.elusivewildlife.com/ Got the kit with red, white and green bulbs. Paid $139 for the kit three years ago. Don't use the red or white.
I've had it for three seasons and it has worked well for me out to 125 yds.
Earlier this year I upgraded to the Wicked 400 from AllPredatorcalls.com.
http://www.allpredatorcalls.com/wic...ght-hunting-rifleman-kit-with-green-led/ I really like this light. It throws a square beam that telescopes from wide to narrow which allows for not so bright as to scare the game up close to providing excellent illumination at distant targets with a narrow beam. I've used it to 175 yds. at night and it illuminates both the reticle and the critter I'm aiming at. Killed over a dozen hogs this year using this light. I bought the 402 set up with green light for $169 IIRC.
I do like the quick attachment device that came with the XLR 250 kit as I can attach a light to a scope in less than a minute. I may use three or four different rifles during the time I am at my lease and it makes it very easy to change. The mounting device that comes with the Wicked light is more or less for permanent attachement but it is a quality mount that has both windage and elevation adjustments.
I don't think you could go wrong with either, but the Wicked light is my current favorite.
Best,
GWB