Antonyms for the phrase "most tampered with" could be "least altered," "unadulterated," "unmodified," or "unchanged." These words are used to describe something that has not been interfered with, manipulated or modified in any way. They imply the purity and integrity of an object, event, or piece of information. Often associated with trustworthy and reliable, these antonyms connote a sense of authenticity and honesty. For instance, unadulterated food or drinks suggest that they are free from harmful additives or preservatives. Similarly, unmodified data implies that it has not been subject to any manipulation or distortion, which enhances its credibility and accuracy.