hi rick and welcome to CPF!
If you like flashlights and in general lights you have found the right place!:thumbsup:
IMO CR2 and CR123 are two different types of battery (CR2 batteries are smaller that CR123) but both are 3V.
so they aren't interchangeable and you can't do a comparison between this two batteries. There are some lights that use CR2 battery type and some that use CR123 (surefire).
I guess the CR123 would be considered "better". It is a larger battery, with much higher capacity than the CR2.
The use of the CR2, and R/echargeable/CR2 has made possible some very small(and very cool!) lights, though.
Welcome to CPF:thumbsup: