Most discussed are brightness, but battery life is also very important. Among the headlights and taillights mentioned here or known to you, which have the best battery life on full charge (stay bright for longest before recharging)?
Alternatively if you know which one have the worst battery life, feel free to mention, too.
I had the $20 magicshine clone that could last about 3 45-minute rides (on low constant setting) before needing recharging, but one day it suddenly died during my ride without warning---without going dimmer, just from bright to completely off.
The taillights I've used (radbot 1000, cygolite hotshot and serfas TL60) could probably last about 3 short commutes, too. I usually set them on flashing mode.
Your question should take into account something that you may not have thought about and that is how powerful a light do you want?
The brightest lights often have the shortest run times, but one might buy a powerful light but only use the lower settings and vastly extend the period between charges.