The word "most cut-rate" refers to something that is inexpensive or cheap. Its antonyms would be words that describe something expensive or luxurious. Some possible antonyms include: premium, top-of-the-line, deluxe, high-end, exclusive, and extravagant. These words connote quality, prestige, and extravagance, which are the opposite of cheapness and affordability. For example, a premium restaurant would offer high-quality food and excellent service, while a cut-rate restaurant would serve low-cost meals with minimal service. So, if you want to express the opposite of "most cut-rate," you can use any of these antonyms to describe something that is premium or top-notch.