golok, Sid brought up some very good points.
I have a number of Surefires, along with a multitude of other lights from Mag, UKE, Princeton Tec, and probably a few others.
For sheer "light power" vs. size, the Surefire will usually win hands down. Since I started carrying a Surefire, I've tended to leave other lights for various mundane chores that I know I'll need more burn time. I have a Photon with me all the time for general lower-level light usage, as well as a couple of others in the garage, or glove compartment. Working on things up close, 60 or 100 lumens shining on something 12" away can sometimes be "too bright", so the Photons, ARCs, UKE 4AAs, certainly haven't been relegated to the "junk drawer by Surefire. When I need light though, I grab my 6P, E2, or M3. On some projects at work, people approach me to use one of my Surefires because it's the only light that throws a great beam and that doesn't "get in the way"
On the other hand, other 123 lithium battery-powered lights, with the exception of the UK 2L, tend to have very similar or equal burn times. For 123 use and decent light, the UK has a pretty good beam (not like a Surefire, though), and a burn time of, IIRC, several hours.
123 batteries are best bought in bulk. 123 battery prices for Panasonic or Sanyo range quite a bit, from around $1.50 ea. at places like Zreiss.com, a bit more from cheapbatteries.com, up to $16 for a pair at your local drug store. Surefire has worked up some specific batteries with a bit more current (1400mAh vs. 1300 mAh), a touch more burn time, around 3-4 minutes, and according to some, a slightly "whiter" initial beam. I haven' tnoticed a difference in my Surefires, though. Even in bulk, though, costs for the Surefires generally range around $3 per. Over time, I don't know if a few extra minutes burn time will pay for itself at nearly double the cost.
If you're looking for alot of light in a small package, without the battery costs, consider one of Surefire's rechargable lights. I currently have an 8AX on order, which will most likely become my GP light, but my E2 will probably be my EDC go-to light.
Sorry for the long-windedness, but JMHO after 5-6 years of Surefire ownership.