There are several synonyms for the word "sonsiest," which means the most hospitable or comfortable. One possible synonym is "coziest," which implies a snug and warm environment that feels safe and inviting. Another option is "welcoming," which suggests a friendly and open attitude towards visitors or guests. "Inviting" is also a good choice, as it connotes a sense of attractiveness or allure that makes people want to stay and enjoy themselves. Other possible synonyms include "homely," "pleasant," or "genial," all of which convey an atmosphere of friendliness and warmth that makes people feel at home.