The phrase "with it" can be replaced with a number of synonyms, depending on the context. For example, someone who is up-to-date with the latest fashion trends might be described as "trendy," "fashionable," or "hip." In a business setting, a person who is knowledgeable about industry trends and developments might be described as "informed," "astute," or "savvy." Someone who is socially adept and able to navigate different situations with ease might be described as "socially savvy," "charismatic," or "suave." Other synonyms for "with it" might include "aware," "plugged-in," "clued-in," and "on top of things".