The phrase "most quaking" implies a great deal of fear or nervousness. Its antonyms would be words that indicate calmness or fearlessness. Some possible antonyms could include "confident," "brave," "fearless," "calm," "composed," "unfazed," or "unperturbed." These words would suggest a lack of shaking or trembling, and instead evoke an image of steady strength or self-assuredness. Using antonyms to "most quaking" might help to convey a sense of courage or tranquility in your writing, which could be appropriate in a variety of contexts.