After beginning to work on it, I think I will likely use both less crit chance and less crit effect. The reason being it is easier to make the different types of armour distinct from each other without just making it a sliding scale of "better".
I basically want to make it so Leather and Metal Armours are approximatly as useful as each other and form the main armours you will see in battle. To this end I've equalised the normal damage, left metal good vs lasers and increased the effect leather armour has vs explosives and flame. In a similar way I think I will have metal better at lowering crit chance and leather better at lowering crit effect.
Then there will be CA as a level above that and slight boosts upon CA for CAII, BoS CA, Enclave CA, Ranger CA (and unique abilities for Enviro Armour)
It is also worth having better critical perk and lower critical perk (or perks, traits and armours) becasue you then have an increased range of options.
better crits vs normal
better crits vs lower crits
normal crits vs normal
better crits vs lower crits
Options is the post wipe buzz word!