I thought some more about my poor post. Not only did I generalize, which is always a mistake, but I dissed AAA lights. And what does better mean? Also, I am a big fan of AAA lights, especially ones with the the new emitters. So last night I took out 2 CR2 lights with comparable AAA lights.
Nitecore Sens Mini Cr2 and Fenix E05 SS 2014, DQG AAA and DQG AAA clicky. They all have a TIR type optic. All have nice floody beams. The CR2 has a slightly broader beam with more output.
Foursevens Mini MLR2 and a bunch of AAA lights (running on both li-ion 10440 and Eneloops). Reflector lights. Generally the AAA lights are more floody. Smaller hotspot and gradual transition to spill. The MLR2 has a bigger hot spot and less transition to spill. On H, the MLR2 has more punch than the AAA lights I played with. I didn't play with my more throwy AAA lights like the Microstream or Tank007 E09 so this just another generalization.
But the bigger circumference of the CR2 can be put to good use. Note that both of these CR2 lights are twisties and don't have the best Uis. Also, I didn't bring my Task Light II out to play.
My post was poor. But there is a reason I like CR2 lights.