I can tell you that I bought the Streamlight TLR-1 a few years ago for my G19, this is what I keep in the nightstand next to the bed.
The box says you should get 2.5 hrs of "regulated Runtime", I got at least 1 hr more out of mine. Fits like a glove on my 9mm, finger toggle switch is very easy to operate and right where it needs to be for both right or left handed ppl. It will certainly light up the room & blind whoever is unfortunate enough to have this light turned on in their eyes.
I keep this light on when I take this gun to the range about once per week and run around 100 rounds or so through it. I have never had any problem with it coming loose or not working afterwards. While attached to my G19 I have dropped it in the dirt, tossed it on a table and shot with it in the pouring rain.
Bottom line... The one thing I can say about my Streamlight is that it works! Given a choice - I would buy another one, It's well worth the money.