When describing a community or society that is diverse and welcoming to people of various cultural backgrounds, the phrase "most multicultural" is commonly used. However, there are many synonyms that can be used to convey the same meaning. Some examples include "melting pot," "cosmopolitan," "intercultural," "multiracial," "diverse," "inclusive," and "tolerant." These words all emphasize the idea of different cultures and ethnicities coexisting and thriving together in a harmonious way. Using such synonyms can add variety and nuance to your language, making your writing or speech more engaging and impactful.