Go Surefire all the way. I used to think that a light was just a light until I tried a Surefire one day just to see what the hooplah was about. Any surefire light will be head and shoulders above any other type of flashlight as far as brightness, clarity, and quality goes. They're expensive, but you do pay for the quality and dependability of them.
If price is a top issue when purchasing the light, then go with a TACM III. It will do an alright job, not fantastic, but acceptable. However, the performance will be extremely lacking compared to the Surefire (not as bright and not as pure of a beam) and I don't think the TACM can take as much punishemnt as the Surefire, so avoid extreme use. I'm not saying the TACM can't take some abuse, but it will most definitely fail before the Surefire. If you can afford it, Surefire will be well worth the money.