The lvl50 ring race... :)

I might be wrong, but I believe someone said that the critical damage range is 30% to 50% and you can't increase it beyond 50% unless a skill does it. So the critical ring still might be better.

The description on the cruel ring in kMS now just says it adds 20% critical damage, not adds 20% minimum critical damage like the skill descriptions do, so I'm not exactly sure what it does anymore. If it does increase critical damage by 20% overall, that'd probably make it better than the critical ring.