Surefire has released the Titan Plus, a keychain-sized flashlight that produces 300 lumens in its highest light mode. Prior to this release, the brightest keychain light produced about 80-120 lumens, so this threefold increase is significant.
Conical 5mm Wide-Angle LEDs are the most durable and brightest Christmas lights available. Almost all professional Christmas light installers use these lights for their displays. Conical LEDs are waterproof and snowproof because they are injection molded into their plastic cordage.
The brightest flashlight that uses AA batteries is the Nitecore Caveman EA81, which shines at 2000 lumens. It takes eight AA batteries and costs about $120. It’s waterproof to IPX-8 Standard (1.5 meters) and impact resistant to 1.5 meters. The Nitecore Caveman EA81 is available on Amazon for about $135. I recommend powering this flashlight with low-discharge rechargeable AA batteries.