Just a little advice from someone who has a few of these Chinese lights. Be mindful in traffic as some of the high power lights throw light everywhere, so you might want to aim it right down in traffic, and only push it up when there is no traffic. They are blinding. I used to use an unlit cycle track on my commutes, and quite a few folk would either leave their high power lights on high, or have them on strobe. It was blinding. They are, however, great for MTB off road.
You can get wide angle lenses for some of the lights. Also don't get too bamboozled by the quoted 'lumen' as most cheapo ones lie and quote theoretical light.
With regards battery packs, some are shocking. The lights from 7 day shop are fine. With these chinese lights, you can, at a later date, get a plastic battery pack which you buy proper quality batteries for. This works out at £30-£40 for the pack and 4 batteries, but it's something you can do later on.