I’ve always liked Wiggle, but I love this: light comparison and beam shots
More cycle shops should do this and then more people would realise a £30 light is not sufficient; to be honest I would spend more on a light than most would on their bike.
My eye was on the Exposure Joystick Mk6
which seems to have a nice beam pattern for road use
but I probably wouldn’t want to spend the money also there are less favourable beam shots, for example on mtbr.com.
My advice is to look around at reviews on the internet first, some will be more favourable than others, but mtbr.com is a good place for checking out bike light reviews as they normally include video and lots of photos. Remember though that photos are only good for comparison if taken using same camera settings, so best to only compare images on the same site.
The imported lights such as the Magicshine brand offer impressive output at a much lower cost, see this candlepower forum thread for details.
For comparison, my three year old AirBike Everlight SL1 (SSC P7) cost £120 new, see this candlepower forum thread for details and lovely beam shots.
Since I’ve also just linked to candlepower forums, worth mentioning that site is a good source of light information, but a little less formal than mtbr.