Explorer's Critical Ring

Generally, +10% crit > +5/10/12 Att

You can't compare the crit ring to evos or angelic blessings.

what a silly statement

of course you can compare them, convert the stats each one provides to a total damage % increase

crit ring is around 4~5% total increase on most people, more static and class dependent (because crit damage modifiers are usually on skills)
evo 3 is probably 4~6% total increase, more variable and level/equip dependent (high attack and high base stat weaken it relatively)