Currently it's a Nitecore MT1A. Full power is 180 lumens from a single AA battery. Twist the head and it goes to a lower power setting. Push-clicky button, which I like. The only drawback is that the pocket clip sucks. Look at it wrong and it'll pop off. So I just stick it in my pocket without the clip. Offhand, can't remember how much I paid for it, but I think it was somewhere in the neighborhood of $50-60.
Also have a Nitecore keychain light on my, well, on my keychain. I think it's about 55 lumens and recharges via USB cable. I think it was around $10.
Previously it was a 4Sevens tactical light, with 2 lithium CR123 batteries. Max output was 360 lumens. Really good light. Usually kept it clipped to my back pocket, but the end of the clip kept tearing holes in my shirts. I even tried applying some Plasti-Dip to the end of the clip, but it didn't help. It was worse than any gun/mag I've ever carried. It now resides in my backpack.
I really want to go back to a pocket clip model. Or maybe I'll just get a mag/light combo pouch and start carrying my Surefire 6P again.
I've got a Fenix PD20 that works very well, but I just couldn't like the tailcap button because you have to push, then release, for the light to turn on. I prefer either a push-clicky, like my Nitecore MT1A, or the momentary-on push button like the 6P.