I have been happy with my Dinotte 5W. Small, bright. Super fast and easy mounting(and dismounting). Uses rechargable AA's. I already owned AA rechargables so I have 4 sets now with fast chargers. So I can carry 2 sets of AA's in the handy holders and swap out on longer rides.
Their bigger 500L looks nice too. And for the price it comes with 2 battery packs, so you can always have one ready.
-D