What was Vivaldi's favourite musical instrument for writing music on?

Antonio Vivaldi's favorite musical instrument for composing was the violin. As a virtuoso violinist himself, he often wrote music that showcased the instrument's capabilities and expressiveness. His deep understanding of the violin influenced many of his compositions, particularly the famous "Four Seasons" concertos. Vivaldi's affinity for the violin is evident in his innovative techniques and the prominence of the instrument in his works.