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