politeness-would like
In certain contexts (requests, for example), the verb "want" may sound too imperative in English (even if it may sound fine to a Spanish ear). In those cases, using "would like" is a better option (it sounds less imposing).
This may be especially interesting for formal texts, or when there is a power relation with the person you are addressing.
I want to speak to you. (sounds urgent and demanding)
I would like to speak to you. (more polite)
I want to express my concern----> I would like to express/voice my concern