I have been through a process of upgrading my lights recently.
I have got a couple of the cheap cree T6 lights, but the batter has packed up in one, where it has gone off twice while cycling round the local reservoir. Not ideal. I also have got a Cateye TL-LD1100, which is good, but recently played silly buggers and turned itself off 7.5 miles into a 45 mile unlit ride. It worked again by tapping it, but the fault continued and hoping it doesn't go off / checking it constantly isn't great. I have retired this light.
I run with lights on during the day at this time of year so I wanted to get something I could be seen by to replace the rear Cateye and have ended up with an Exposure Flare. It is very bright and I think will do the job. I got it as part of a pack, so it came with a charger and a Flash (front light. The front light will be fine for daytime riding / in poor light conditions, but wont't light the unlit roads.
I have decided to replace the Cree T6 with Exposure lights too, as I have been impressed with how they are made etc. and want something I can put my faith in when riding at night. The T6 is supposed to give plenty of warning of running out, but by the time it tells you it's running low, you have around a minute.
The exposure route might be more expensive, but I want to be seen and to see and have faith in both.
I also light the quick release nature of the exposure brackets, which means the same lights can be used on different bikes. I shall have a pot of spare / redundant lights...
I see rear lights as a safety device and am not going to scrimp on this. I'd rather spend £30 extra and been seen. And you really can't fail to see the Flare when it is going, it is called a Flare for a reason