I have used a Surefire E2D Defender for years. Bright enough to preflight a large aircraft, but way too bright for the cockpit. It's also good for walking around town on a layover.
For a 172, which is what the OP is flying, I have a Coleman MAX. LED, red, white and green light. I like the green for night flight in the cockpit/simulator and the white provides enough light for preflighting said 172. It also has a lanyard feature, which is handy.