Just be very wary of the cheap Chinese LED's you find on
eBay etc. I guess we all want the best light possible for the cheapest price, but this technology cost a bit more for a reason. A cyclist friend of mine, who works with electronics for an aerospace company, tested a cheap Chinese light that his brother had bought and was so concerned about the potential safety issues with the battery / charger set-up that he posted a report on his findings on a local Facebook cycling group. They're probably not ALL bad, but if you buy through a reputable shop or site you'll have a bit of extra peace of mind that the product is up to a standard.
I'm going to see if I can somehow post my friends report on these lights on here, but getting something off of Facebook and on to here might be a bridge too far for my limited technical brain!!
Personally, I use a Lezyne Micro Drive 400 XL at the front, and a Moon Comet R at the rear. I've always found the 400 XL plenty good enough to see by, but some of the higher output Lezyne lights seem to be on offer at various outlets at the moment. The Comet R is a fantastic light and really useful on its highest setting (35 lumens) on foggy days.