Apologies to the Talking Heads.
I am a light junkie. It started innocently enough with the purchase of a Dinotte system, and then escalated into dynohubs, helmet-mounted lights, and secondary lights. I make no apologies for my addiction, however, as it enables me to ride more safely under the cover of darkness.
After much experimentation, I've determined that my favorite head light is the B&M Lumotec IQ Cyo R. This generator-powered light lays down a very useful swath of light that works beautifully for my commute. Said commute is 11.5 miles (one way), and consists of city, backroad, and suburban roads. It's efficient enough that it puts out enough light even when chugging along in the granny 'ring, and offers enough throw that riding at 25mph is comfortable. It's not cheap (approx $110)--especially when you add in the cost of a dynohub--but it requires no batteries, no charging, and is available at the turn of a switch. For those who don't have (or want) a dynohub, the battery-powered Ixon UQ has an almost identical beam, and can be recharged without removing it from the bike.
When motorcyclists and other cyclists comment on your tail light's brightness, you've found the right one. Dinotte's 140L has been my first choice for both daytime and after-dark visibility. The three flashing modes work great for my morning commutes, and the three steady modes offer enough firepower to illuminate guardrail reflectors half a mile behind me. The o-ring mounting system may seem funky at first, but it's versatile and more secure than many competitors' plastic clamps.
As much as I like my Dinotte lights, I found them a little too heavy for helmet use. Enter Princeton Tec's EOS. Tipping the scales at a svelte 105g (with batteries), it's light enough that I don't notice the extra weight on my helmet (by comparison my Dinotte's battery pack weighs over 140g). On low, it puts out enough light to illuminate street signs and make adjustments to the bike. And on high, it's bright enough to use as backup should my main headlight fail. And for those times when I want a little extra protection against inattentive morning commuters, I set it to blink mode.
Shimano makes the dynohub (DH-3N80) that I use, and Universal Cycles laced it to a 32h (700C) Velocity Dyad rim. I purchased lights from Dinotte, Peter White Cycles, Longleaf Bicycles, and eBay, and didn't receive any compensation or discount for blathering on about these products.