One of my favorites has been the Blackburn MARS 3.0, it doesn't cost much, has a good mount, 5 red LEDS, three modes of operation and the light also has two side (amber) LEDs. I chose that one for my road bike. I also use a Vista 5 LED that has worked for years.

P.S. I use flashing lights in daylight hours due to shady roads, tunnels and underpasses. All those things that can make a bike invisible to a driver with dark sunglasses.