For an all in one light i have a Full Beam Fusion light, which is really nice, really good beam pattern, more than bright enough to be used on it's own without a helmet light.
It has a magnet on the wheel with a sensor (much like a speedo) which automatically dims or brightens the light depending on speed, which works nicely.
It has a number of settings so is very tune-able to your riding and runs for about 4-5 hours or longer if you choose lower power settings, with approx 3000 lumens i normally run it at a lot lower and do not feel i am missing out compared to riding friends.
I have had this light for just over a year now, ran it all last winter for night riding and commuting and it does the job really well.
It is not cheap but it does work incredibly well.
For comparison before I had Ay-Ups, which are great lights but a little lacking on power (but great for racing) and I have also ran the Chinese lights which people commonly link on here, which were also good as well.
In terms of cost then the full beam loses, but in terms of quality of light, functions, quality of manufacture and company support as well as supporting British manufacturing then it is great.
I had a problem with the switch and it was replaced with no arguments and they also paid the postage both ways.
I think the main difference is the cleanness of the light you get compared to other lights I have had.
I realise loads of people will probably say it's a waste of money and you can get cheaper lights which are better etc but they are definitely worth a look if you are after a single light which just works all the time with out any hassle.
So overall I have been very impressed.
If your anywhere near Southampton your more than welcome to try mine.