The MR-71 is the best sounding tuner Mac has ever made. It is not the most selective or sensitive; that title belongs to the MR-78. However, in stock form, none of the other tuners sound better. The MR-67 is close.
The MR-77 is the high value Mac tuner. Frequently found in good shape for under $600, it has many attributes of the 71 and 78 but costs less than both.
Hope that helps.