Antonyms for the phrase "most ill at ease" could be "comfortable," "confident," "relaxed," "calm," or "at ease." These antonyms refer to a sense of ease, contentment, and relaxation, which are the opposite of feeling uncomfortable, awkward, or unsettled. Being comfortable in a situation means feeling secure, safe, and relaxed in one's surroundings. Confidence refers to a sense of self-assurance, trust, and belief in oneself. Feeling relaxed implies a state of calmness and ease, while being at ease reflects a sense of belonging, acceptance, and peace. Therefore, choosing antonyms for "most ill at ease" depends on the context in which the phrase is used, and what the user intends to convey.