Most undiscriminating means lacking in discernment or judgment. Antonyms for this word would include discriminating, discerning, perceptive, selective, and wise. Discriminating means having good judgment or perception. Discerning means having or showing good judgment or insight. Perceptive means having a good understanding or insight. Selective means carefully chosen or chosen with great care. Wise means having the ability to make wise decisions or judgments. These antonyms emphasize the opposite of undiscriminating, and each word has its own unique connotation, conveying the idea of sound judgment, clarity of perception, and the ability to make good decisions.