Best CR2? Other questions

[etc]

So what are some higher quality CR2 cells?

There is a variety on the market, like Energizer (in several permutations), Duracell, Kodak, Maxell.

 

[etc]

Also, when is CR2 considered dead?

It starts from 3.3V.

 

[LumenHound]

I've been supplying my brother with Sony and Duracell branded primary CR2 cells and he reports identical life from either brand.