The antonyms for the word "most grass-roots" could be words like elite, establishment or mainstream. These words represent the opposite of grass-roots, which usually implies a bottom-up, organic movement. Elite describes a group of individuals who are considered to be superior in terms of wealth, social status or education, and often hold the power and influence. Similarly, establishment refers to a group of people who control the status quo and resist changes. Mainstream is often associated with popular, widely accepted ideas or products, reflecting the top-down approach. While these antonyms represent a different perspective, they do not necessarily imply a negative connotation.