What are you trying to do with your lights?
- do you need to light the road/trail?
- do you just need to make sure you are seen, but have enough ambient light to see by?
For me riding in the city - my main concern is being seen so I go for multiple inexpensive LEDs front and back.
I find that I can get enough light to see by for short stretches of dark bike paths by putting my front white LEDs into constant on mode vs. the flashing mode I use on the road. Not useful for long sections where you want to ride at a decent clip though.
If I am doing a night ride in a rural area my main concern is actually lighting the road and I use two cateye halogen lights that take 4AAs each - HL 500 II.
http://www.chainreactioncycles.com/M...x?ModelID=1234
You can definitely get brighter lights both using batteries or a hub generator, but I find the lights I am using are inexpensive, easy to install remove and transfer to another bike and decent battery life.
If you can tell us more about your lighting needs we can target our advice a bit better.