Take a look at
this thread for some ideas.
Personally, I like (in order):
*
Ra Lights (mine programmed to come on in high mode) - I think these are some of the best and most flexible lights out there. Rugged, reliable and versatile.
*
Surefire - excellent quality, super reliability and usability, but tend not to be on the best deal, or the most technically advanced.
* Fenix lights (
tactical series) - super bang for the buck.
-john