The antonyms for the word "most unstirring" are many, including "lively," "animated," "energetic," "vibrant," "dynamic," and "thrilling." These words evoke images of action, movement, and excitement, all of which are diametrically opposed to the passive and uneventful connotations of "most unstirring." Other antonyms may include "dynamic," "active," "stimulating," and "engaging," all of which suggest an element of excitement or interest that is absent from the term "most unstirring." Ultimately, the choice of antonym will depend on the intended context and the shades of meaning that the writer wishes to convey.