I use HM65R-DT its well built, USB rechargable and just uses a standard battery that you can swap out. The interface is nice with individual buttons for each beam type and a visual indicator for charge level. I never run it full brightness and it easily lasts me full rides through the night and on a...

I've got a Cateye Wearable X, charge lasts a long time and it's small. The only negative is that it looks like it's £30 now! I found one of the knock off versions of the Lezyne Zectos you can get on amazon in the road yesterday. It seems to work well and I've got no use for it. DM me a postal addres...