Something bright and well-mounted to the bars with a battery that lasts for the entire ride. After that, the brand seems irrelevant.
I run a CatEye of some sort and then stick a Petzl RXP on my head. The combo works well and I can recharge/top off the batteries using a USB plug in my truck before and after the ride.
The People's Lights coming out of China are cheap and bright, but you'd better be prepared with a backup battery and light source because the battery life is jaaaanky.