I have 2 Cygolite headlights and 2 Cygolite taillights. Over maybe 5 years the lights have been flawless though one headlight housing cracked where it swivels. A little epoxy fixed that but it doesn't swivel now.
I use them in flashing mode for daylight riding and charge them weekly (6 - 10 hours of riding) and they've never gone dark.
If I rode at night I'd look for something with a flat-top beam pattern like an automobile headlight.
In another thread someone mentioned the Garmin Varia RTL515, a taillight which contains a radar unit. After reading a lot of positive reviews I got one and I love it. It lets me know if anything is approaching from behind and shows the number and distances. I find it warns me much sooner than a mirror or my ears. The display can be a phone, a compatible Garmin bike GPS computer, or a small dedicated display (I use the latter). The units are small, inconspicuous, and simple. I strapped them on the bike, turned them on, and everything just worked. No wires, no reading manuals.
