The phrase "most sought after" refers to something that is in high demand or very popular. There are plenty of synonyms that can be used in place of this phrase, depending on the context and the intended meaning. Some options include "highly prized," "in-demand," "coveted," "popular," "desired," "sought-out," and "in vogue." Each of these words conveys a sense of value or desirability, making them suitable alternatives to "most sought after." Depending on the tone and emphasis of a sentence, different synonyms may be more appropriate than others. Regardless, all of these words suggest that the thing being discussed is well-regarded or highly valued.