The term "more first string" implies that something or someone is of a higher quality or superior compared to others. Antonyms of "more first string" can include "secondary," "inferior," "substandard," "mediocre," "second rate," "unimportant," and "less significant." These words can be used to describe things that are not considered top-notch, such as second-string players in a sports team, minor characters in a movie or book, or less valuable items or products. In contrast, "more first string" can refer to the very best, most important elements of something, such as the A-list actors of a movie, the star players in a sports team, or the top-performing products in a company's lineup.