Collation vs citext

Looking to create a unique index for some fields and we do not want the uniqueness to be case sensitive, meaning Help, help, and heLp are all the same. Is there any performance impact/benefit to creating a collation vs citext?

CREATE COLLATION case_insensitive (  
    provider = icu,  
    locale = 'und-u-ks-level2',  
    deterministic = false  
);