How large of a light do you want? Does it need to fit in your pocket? Budget?
My daily carry is a Fenix PD 32 UE, but there are newer, brighter models out there, like the PD 35. Most of these use rechargeable 18650 LI batteries.
Check out Fenix, Jetbeam, Eagletac, Olight, and several other manufactures. Check out goingear.com. He sells a lot of these lights and makes youtube reviews on many of them.