Geez...What a question?!!? I think I can narrow it down to a top 5.
1) Surefire L1, with green LS. This is probably the coolest flashlight that I have ever owned. It is the first flashlight to replace my E2 for daily carry. Rather expensive, but worth every penny IMHO. I was not as impressed with the white LS version that I had. It lacked the throw and 'brightness' of the green.
2) ARC AAA, white or turq led. Super small, tough, reliable and bright.
3) CMG Infinity Ultra / Regular Infinity in red or green. Cheap to feed, tough, reliable and bright for the runtime. The regular Infinity with a lithium battery dropped in it makes an excellent stash light for emergency kits.
4) PT Attitude. Same rough size as a Minimag. Cheap, waterproof, tough and lots of useable light for a long time.
5) Photon II. Small enough to carry several of them all the time and never feel them in your pockets. Battery life is fine as long as you just use them intermitently. Only big drawbacks are mildly annoying battery changes and total lack of water resistance.